The Trouble with the Word “Invasive”


This is a long-simmering rant about the many ways the term “invasive” causes confusion, and more.  DO weigh in with alternatives, pushback, and rants of your own.

“Invasive” as synonym for “nonnative”

Google “native versus invasive” and the 5.6 million hits confirms my observation that this is a common usage, and it’s led to a common misperception in the public that the opposite of native is indeed invasive.  QED: nonnatives ARE invasive.  Even regular garden writers sometimes use this juxtaposition, which should more accurately be “native versus nonnative” or I guess, “exotic.”

That great leveler, Wikipedia, confirms this problem about the term “invasive”: “The first definition, the most used, applies to introduced species (also called “non-indigenous” or “non-native”) that adversely affect the habitats and bioregions they invade economically, environmentally, and/or ecologically.”  At least their second definition is more accurate and even includes native species like deer.  No argument there.

Defining away the invasive behavior by natives

Can native plants be invasive?  Sure, as evidenced by the above-mentioned deer or in the plant world, wild grape.  But when native plants are termed invasive someone invariably pipes up to correct the writer because by definition, they’re nonnatives only.  And sure enough, legally, by the official U.S. government definition, only nonnative plants can be deemed invasive – for purposes of qualifying for money to remove them.  The 1999 Federal Executive Order on Invasive Species defines an invasive species as a “species that is not native to a particular ecosystem…”

Invasive plant lists covering large regions – even continents!

We all know that plant behavior depends on the exact conditions the plant is growing in, as well as more broadly, the region.  So some plants that behavior well in the North are overly vigorous in the South.  Or some, like the infamous purple loosestrife, are vigorous in wet spots, not in dry ones.  Examples abound.

Spirea and Doublefile Viburnum (L), Lespedeza (R)
Spirea and Doublefile Viburnum (L), Lespedeza (R)

Yet this site by the U. Georgia and many other sources, including the National Park Service, don’t distinguish by region, and the resulting list of “invasives” includes these surprises to gardeners near me: several viburnums, two verbascums, several veronicas, red and white clo0ver, Japanese yew, 3 spireas (MOST on the market), various salvias, willows, nandina, grape hyacinth, Miscanthus sinensis (without specifying that it’s only the early-bloomers that spread), Lespedeza thumbergii, Pee Gee Hydrangea, cotoneaster, and strangely, littlestem bluegrass (Andropogon virginicus).  Yet native thugs like trumpet creeper are encouraged and they’re not invasive?

That designation of Spirea really bothers me because it’s such a self-sustaining, easy, low-maintenance and well behaved shrub, one I’ve grown for 30+ years with no signs of trouble.  And yet another source – the  USDA National Invasive Species Information Center – also targets Spirea Japonica and says this about it: “Spreads rapidly and forms dense stands that crowd out native species.” This and other contradictions between official reports and in-garden experiences growing targeted plants is puzzling to me.

Adding to the overly broad regionality of invasive-plant designations, there’s a new book on invasive plants, written for a national audience.

Shouldn’t invasiveness be designated locally?  And sometimes, for certain conditions?

“Invasive” used instead of “spreading”

I’ve heard garden-club members describing their passalong plants at plant swaps as “invasive” if they spread at all.  Which leads to said garden club being accused of encouraging the use of “invasives,” among other things.

Methods of “invasion” all lumped together

Mature English ivy
Mature English ivy

The  USDA lists these characteristics of invasive plants: “produce large numbers of new plants each season; tolerate many soil types and weather conditions; spread easily and efficiently, usually by wind, water, or animals; grow rapidly, allowing them to displace slower growing plants; spread rampantly when they are free of the natural checks and balances found in their native range.”

Yet some of those qualities are valued in the garden – especially tolerance of many conditions.  And for the gardener on a budget, especially one trying to replace their lawn with another groundcover, spreading is a good thing and it’s usually described more positively as “fills in quickly.”

What if the standard were: Does the plant spread in a way that causes harm to natural areas?  For example, plants that are spread by bird, like English ivy, so that the seeds can go everywhere and harm natural areas.  Unlike Spirea and Nandina that spread by rhizome and produce a couple of offspring every year, if that – just like Itea does?  Or if it’s simply spreading in the garden, is it impossible to control, like running bamboo?

For example, “Invasive Species of Concern” in Maryland includes mostly plants we’d all agree are thugs and not even considered garden plants, but daylily?  As a sun-lover, it won’t spread into the woods and even out in the sun, how hard is it to dig up?

Or a plant could be harmless in a townhouse garden on Capitol Hill but potentially harmful if planted on the edge of a forest.daylily

I wish there were several terms used to describe spreading behavior by plants, rather than the single term “invasive.”  How’s a gardener to choose between groundcovers like pachysandra, periwinkle and English ivy, when they’re lumped together as equally thuggish when only one of them will grow virtually to strangle trees, set seed and spread indiscriminately?  

More science-based info, please

In researching the topic of “native versus exotic” I came across one example of the type of reporting on invasive species I’d like to see more of – based on research, not scare tactics.  Just one quote from this article by Cornell will piss off some readers, but here goes:  “A small percentage of plants exhibit invasive tendencies, while the majority of plant introductions are benign or beneficial.”

Solutions for “invasiveness” coming?

Plant breeders are hard at work breeding out invasiveness in popular garden plants, as reported on the Native Plants and Wildlife  Gardens blog.  Though controversial, especially among native-plant advocates, this type of breeding is recognized by pragmatists as a step in the right direction.

Daylily photo credit.


  1. Susan, I think your take on this is both level-headed AND mistaken.

    Virtually every expert I’ve ever discussed this with agrees that invasive plants have two characteristics:

    1) they are not native to the area being discussed;
    2) they cause environmental harm because they self-perpetuate.

    To be invasive, the plant must be both things. And I think that is the only helpful way to think about it.

    Can native plants act, in a garden setting, in an aggressive or unbecoming manner? Of course they can.

    But they unlikely to disrupt the surround ecosystems because of that aggressive behavior.

    Do we have too many deer? Surely. But they aren’t invasive because they haven’t invaded anything: they belong here, just not at human-assisted levels.

    I’m a fairly passionate advocate of native plants (that’s all I use in my gardens) but I do agree with you that some like-minded advocates are sometimes guilty of sloppy labeling.

    I think there are lots of great reasons to use native plants, mostly or exclusively, and that fact that a small number of invasive plants are doing a lot of harm is one of them.

    You are right to argue for more regional specificity on this topic, by the way. Nandina and daylillies ARE invasive some places in the U.S. but less concerning elsewhere.

    • I was going to attempt to write these same comments, but Vincent beat me to it.

      There is a real difference between a vigorous native and an introduced invasive when it comes to environmental harm. I may not want a vigorous native planted in my garden where I have to manually manage it, but that doesn’t make it “invasive.”

    • The larger problem here is people (the author, many posters) having incredibly strong and completely uneducated, if not misinformed opinions. Everyone: don’t you want to do some research before posting your thoughts to the world?

      The very idea that one person’s experience in their garden should trump available ecological research is confusing to me. Do you pro-invasive posters really feel yourselves better able to judge than scientists who research this stuff for a living?

      There are some interesting conversations going on now about native plants “vs” exotics and their place in design, see Thomas Ranier, among others. But this whole “pro-invasive” movement is so misguided and selfish.

      What I hear is that you really want something so you should be able to buy it, and plant it without regulation, because you really want to, and the whole of ecological research should take a back seat to that (you’re on a budget!).

      Can’t we do better than this?

        • Thanks, Christopher! We’re starting to see in the comments some examples of why people hesitate to discuss certain topics, like this one. Another example? The many emails I’ve getting from people who agree with my post but won’t do it publicly in a comment. They’re afraid of losing their jobs.

          • And Susan, I have to say I’m confused. I read through a couple of your other pieces and you seem to be a fairly ecologically-minded person. Aside from you’re issues with common uses of ecological terminology, do you really feel that people should just plant whichever plants they personally deem ok, and ignore invasive species regulations?

            In NY right now, the DEC is trying to get a short list of seriously damaging invasive deemed prohibited or regulated. Many nurseries are up in arms and launching campaigns to try to get barberry and various Euonymus species knocked off the list. These are plants that I’ve watched destroy (with the help of deer and people) many of our forests. But still, because of industry lobbying, they might go unregulated.

            This desire for anything, anytime regardless of what “experts” say can be truly damaging. I think it would be difficult to really understand the research, education, and effort involved in regulation, and to then dismiss them as the opinions of people who probably know less than you.

          • Rebecca, I suggest you go back and read the actual arguments presented and then discuss them instead of twisting the arguments into gross caricatures. No one has argued what you are saying they have. FWIW, what you are doing is arguing a strawman logical fallacy.

          • Hi SKR,

            I went back and reread. I am getting a little carried away, you’re right. The main point of the piece is about common use of terms and I feel like that’s such an easy fix, I sort of side-stepped it to focus on the other aspects of the article that got me more annoyed, as well as other things other people were posting, that seem incredibly irresponsible.

            Back to the article: Where exactly do you see me attempting a strawman fallacy? After reading Susan’s profile, it seems like she’s from Maryland. Maryland has daylilies listed as an “invasive species of concern.” Some quick research seems to indicate that Maryland doesn’t have a prohibited species list, so this is the best they have to offer. But the author laments the daylily’s inclusion on the list and thinks she knows better about the plant’s behaviour than the list makers. Go ahead and reread, this is what she said.

            I guess it’s a bit of a jump then to assume she’s not exactly against planting it in the garden, but it’s not much of a jump, is it? It would be nice to know… Susan?

            But you’re right, I got a little carried away being stuck in bed yesterday. You’ve got to remember though, this is GardenRANT. I personally wish it was GardenDebate-until-you-reach-consensus… perhaps someday.

        • Well Done Christopher.

          And you too Susan Harris, a truly excellent Rant.

          This from a 22-year professional gardener and naturalist with a BS in horticulture from a top program. Not every scientist is doing a great job (some of them were C students ya know) and there are hardly any scientists who do a great job of imparting information to the public well (I’ve worked in the field with archeologists, chemists, primatologists and marine biologists and have heard some horror stories about poor quality experiments and studies).

          And don’t get me started about journalists and garden writers who also only get the story partly right. Plus they live in an environment where a scary story (“Zombie Invasives on the March!”) gets readers and so creates a positive feedback loop when they overstate the case on invasives (I’ve written for three newspapers and nine magazines).

          So there are plenty of well-intentioned lay gardeners who get the story only partly right and then pass it on to their peers, garden club, etc. like a kid’s game of “telephone.”

          And please, let’s set aside the mistaken notion that any native plant or animal that is spreading is automatically exempt from the notion that its presence is disruptive to the environment. The deer population in nearby Duke Forest is so high that native plants are going locally extinct since they can’t reproduce before they’re nibbled to the ground.

          The most succinct description of the overall problem here is the human tendency to subscribe to some easy dogma, such as : “non-natives are always invasives,” “spreading is the same thing as being invasive,” “anything invasive in one state must be invasive all over the country,” “natives can’t possibly hurt the environment,” etc.

          Human brains are capable of grasping the nuances that Susan Harris accurately describes. To do otherwise is simply choosing to be a dogmaniac.

          • Hi Frank.

            Are you familiar with the term “straw man”?

            No one in this thread has made the argument that native species cannot be environmentally harmful. Deer is a clear example of a native species causing much damage (while of course understanding that the actions of people are really what has lead this animal to ravage our plants as they do). What posters *are* saying is that, regardless of the damage deer cause, it doesn’t make them “invasive” as they are, by definition “native.”

            Other things no one has said here:
            “non-natives are always invasives,”
            “spreading is the same thing as being invasive,”
            “anything invasive in one state must be invasive all over the country,”
            “natives can’t possibly hurt the environment,”

            There are two competing narratives going on here:
            1) Terminology and the problems that arise when people use words wrong
            2) The desire for gardeners to continue using plants that researchers have deemed ecological harmful

            After reading all of the below (I’m stuck in bed) it seems like #1 has been solved, right? And we can go on to debate #2?

        • I wish it were true that there were no pro-invasive people here, Christopher, but the sad truth is that there are.

          A cornerstone argument in these pro-invasive rants is this:

          X is listed as an invasive plant.
          I’ve never seen X become a problem in my garden.
          Therefore, I’ll plant X anywhere I please.

          The author of this post put nandina, daylillies, and spiraea in this category of plants she loves too much to stop planting despite evidence from biologists and ecologists that they are problems.

        • Hi Christopher, You don’t see pro-invasive posters here?
          David McMullen is pro-daylily.
          Alan’s post is pro-running bamboo!
          And the author is pro-nandina, spirea, miscanthus, and many others whose invasive tendencies are solid.

          Semantics here (an easy fix if you read the other posts, or had done proper research) are a red herring for the fact that many just want to continue planting invasive plants without blowback.

          • As Susan pointed out in her piece, the term “INVASIVE” is used imprecisely. What is aggressive in one region isn’t so in another. When something is demonized as invasive, it is effectively tagged as a criminal plant, when in fact, the reality is more complex. It is so easy to call something bad and cross it off a list entirely – if YOU want to do that, fine, but allow those of us who have a more nuanced approach to our words and our gardening practices continue with our deliberate engagement with the planted world.

          • Hi Ivette,

            As far as I can tell, the terminology aspect of this rant is pretty settled right? People use words wrong. It’s easy and important to distinguish between invasive and exotic. Cool?

            But when government agencies FINALLY get through the incredible layers of bureaucracy and industry lobbying to make these pathetically skeletal lists of plants prohibited, we should respect that. Do you disagree with this? Does anyone? This is what has my panties in a bunch. The idea that it seems to me like a lot of the people in this room feel like their personal feelings should trump DEC regulations.

            As someone who talks to people about plants with unusual frequency, I listen to people all the time who say things like “Well if they don’t want me to plant barberry, I don’t care. I’ll just pay the fine.” I have never once encountered an ecologically educated person who has said this. These are “normal folks” who just want what they want. And when you point out the damage, and the link to lyme disease, they almost always opt for a purple Physocarpus.

            So I guess that’s the question, the guy who walks away with the barberry, is that a “nuanced approach” in your mind? Is that a “freedom” we should all respect?

          • Rebecca, I’m not “pro daylily”. I am pro using your damn brain! I clearly stated that you shouldn’t plant Hemerocallis fulva in a marsh. I also said that it should be planted in a garden if you want to.
            If you live in a marsh – maybe a bad choice! See? See how making decisions works?
            The distinction is that one place is not a good choice and one place is. The goal is to make the right choice.
            Adult humans are required to make educated guesses and decisions every day.
            We rarely use glue to wash our hair and we rarely put out a fire with gasoline.
            I believe that gardeners, with a little guidance and information, can also act as adult humans and make choices for themselves about what they plant in their urban/suburban yards.
            We make many decisions in a day that affect the environment. I’ve decided to plant daylilies in my garden because I am many, many miles away from a marsh.

          • Hi David,

            Would that gardeners could be relied upon to use their brains responsibly! Would that people in general could be relied upon…

            Do you really think that all of the daylilies that are in ditches are there because people planted them there?

            One of the characteristics a plant needs to exhibit in order to be prohibited or regulated is a tendency to spread beyond the garden, even when only planted there.

            The reason we have laws and regulations are because people can’t actually be trusted to always behave in the most logical manner. We require guidelines to help us along. And of course, we all can’t have advanced degrees in ecology, so guidelines written by people who are professionals in this area, are meant to help those who are not make the best choices.

          • The whole point of the original article at the top of this thread was misuse of language. To call people “pro-daylily” or “pro-bamboo,” when they said no such thing, is misuse of language. “not knee-jerk anti-non-native plant” is not the same as “pro-invasive.” The distinction is not subtle, but it seems beyond Rebecca and Vincent.

          • Hi Skeptic,

            How is posting about how it’s ok to plant daylilies, even where proven invasive, not pro-daylily? <– An invasive. And by extension pro-invasive? Enlighten us.

          • Aw, fer chrissake Rebecca. He didn’t tell you, or anyone else, to plant daylilies. He said in some places they may be appropriate and some places clearly not. Nor did he denounce them as uniformly evil. But it’s this last fact that gets him the perjorative label “pro-invasive.”

          • I should have added: Alan didn’t advocate for anyone to plant running bamboo, either. He just said his neighbor manages to control. In that case I again consider it misuse of language to call him “pro-invasive.” (or even “pro-bamboo)

      • This is such a bad continuum of horticulturists holding onto really crap plants by using similar arguments the gun control opponents use. Picture Charleston Heston clutching a Miscanthus and proclaiming, “you will not stop me from using this plant unless you can pull it from my cold dead hands!” What is happening here is so twisted but what I don’t get is why the hell would you use such garbage plants when so many alternatives exist? Bottom line for these folks, walk into a degraded ecosystem devoid of natives, observe the paucity of animal life, and then tell me it is more beautiful, more total species rich, and providing ecosystem services at a high level?

        • But I thought we were debating garden plants here… if a garden is nothing but a degraded ecosystem then why are we here talking about this? – but my stance is that a garden is a part of human development and therefore is not nature or ecosystem and has a resonant cultural and artistic value that makes it worthwhile.
          Everything we as humans do on this planet has an effect on the environment. Are we tearing down football stadiums or art galleries or airports because they’re bad for the ecosystem? Nope. So why the big attack on gardening?
          Lets not fall into the all-or-nothing trap of the gun debate and recognize, collectively, that gardeners should make responsible decisions and support each other’s decisions through conversation and information sharing rather than condemn and berate.
          Lets also remember that we won’t all make the same decisions.
          And Miscanthus has not proven to be a problem in my area – so why should I have to give it up?

  2. Please piss off some folks!! I’m sick of the stereotyping of all non-native plants as “invasive”. truly only the smallest percentage of garden plants end up causing trouble…
    With that said, tawny daylily (hemerocallis fulva), the common “ditch lily” is pretty invasive in marshy areas. Don’t plant it in a marsh. Do plant it in a garden.

      • But it’s also why some haven’t. I can plant daylillies all day long in the interior valleys of Southern California and they aren’t going to invade. Yet I have heard people complain in those same areas that they are invasive because they read it in some Eastern US garden blog. Same thing with Pampas grass. People see one of the sterile (pretty much) cultivars and they freak out even though they are being planted where even the species won’t invade.

  3. Yikes, the daylily. I have seen huge swathes of ditches completely choked with the ditch lilies. At our new (old) cottage the previous people put some ditch lilies in front of the house. They have been extremely difficult to get rid of. When you think you have, another shoot comes up from a little piece that you missed, or they get themselves in between the rocks and are impossible to get the whole thing.

    I have seen sections of the edges of forests where periwinkle had escaped from somewhere, no house even close by, and there isn’t a native wildflower left.

    I am extremely careful about any plant that I introduce at the cottage. We are on the edge of a forest, and I wouldn’t want to be the cause of losing any of the native orchids, or ferns.

    Now can we just get rid of all the darn Norway maples?

  4. Native species can be invasive because of highly altered habitat. So deer and fox grape are both edge species and human activities have generated a lot more edge such that most of our forest patches are now “edge”. But it is true that lots of exotics remain well behaved, but it depends on location. In the tropics of far northern Queensland were I worked for many years lantana and privet were both horribly invasive and real problems. So invasiveness varies with locale.

    • Yes, artichokes and cardoon are both invasive. Not a problem in residential gardens, though, unless you’re living at the margin of wildlands. Even at a place like the Albany Bulb (edge of Berkeley where a tiny bit of unmanaged land juts out into the SF Bay), you can see artichokes or cardoons happily setting seed and taking over. They can get huge and will live without watering — though in this dry winter, it will be interesting to see what survives.

      • Artichokes as invasives seem to make the point of this article. If I want artichokes to winter over, I dig them up and take them indoors. They are just never, ever going to go wild in Maine. I might be crazy for trying to grow them, but they are not Purple Loosestrife waiting to happen.

  5. Thanks for putting it so eloquently Vincent. I couldn’t have said it any better. And many states are working on regional/state assessments for plants – so it is happening.

    I just had a point of clarification on the article. I don’t think that anyone calls andropogen virginicus little bluestem. While common names can be confusing, I think it is pretty widely accepted that little bluestem is schizachyrium scoparium. Andropogen virginicus is often called broomsedge bluestem – but that doesn’t even really matter – the point is – that no, the common native grass little bluestem that many gardeners might have heard of is not listed as an invasive plant somewhere.

    Broomsedge blulestem is, but if you look at the site that you linked to, it has only been reported as invasive in Hawaii – which seems reasonable that a plant native to the eastern US could be invasive in Hawaii – which has a very distinct set of species from the rest of the continental US.

    Yes- sometimes the invasive/native issue can most definitely seem confusing – but we don’t want to make it more confusing than it really is!!

    • But by calling it the “invasive/native issue” you are perpetuating the confusion. Invasive/native is not a dichotomy. Invasive is not the same as non-native. That’s what I understand Susan’s point to be, and she’s right.

      Sometimes people use “invasive” and “non-native” interchangeably out of garbled thinking. Sometimes it is a rhetorical device to attach a pejorative term (invasive) to plants they just don’t like (non-native). In either case it makes the discussion more confusing than it really is.

  6. Great article. Over the last few years I have grown weary of the Cult of the Native and the inability in various gardening circles to profess love for an exotic without all hell breaking loose. Native plants are wonderful plants in the landscape, but “invasive” is too often incorrectly applied to non-natives and now has taken on a politically correct life of its own. The native vs. non-native argument implies that ecosystems must remain static to some imaginarily balanced pre-European Utopia…but what of those seeds that crossed the Bering Strait sown into skins 6,000 years before? Gardening as we all know follows trends, and this trend is solid gold right now. I for one am happy to share this article with others who are not experts on Natives but are nevertheless quick to jump on the bandwagon in righteous indignation.

    • No, the native / non native debate does not presuppose static pre Europoean utopia. I’m get real tired of this being the #1 critique of folks who advocate for native plants, because we native plant people know how nature works. The larger point is we have so altered the world that EVERYTHING is now a garden, a novel ecosystem, and we’ve forced ourselves to have to manage the world as a gardener. We’ve proven quite inept at this ability, not knowing what we’re doing, not having enough resources, leaping before we look. Human nature I guess. More native plants, more connection to home, less McDonaldization of the world, more wildlife, more ecological redundancies — just common sense and community building for the future.

      • Benjamin, “We native plant people know how nature works” – I am with you on MANY fronts, but I have to take issue with the language that you (and others, like Rebecca – I only comment to you because I feel you and I can deal with opposition and not get crazy – I don’t know, maybe I’m assuming?) use implying that those of us who don’t hold to the same ideas are not educated and don’t understand the ecological impact of our choices.
        I very much agree that thoughtless planting by those only interested in aesthetics has done immense damage, and that thoughtlessness has to stop. But education shows me that this is NOT A BINARY – native only planting is just as shortsighted as exotics only. The reality is that yes, our landscape has been altered by our hand – but we are a part of the nature that we are trying to bolster and protect. It all comes down to education and implementation, in my opinion … learn as much as you can about where you are and don’t get swept up in the dogma of either side.
        Assuming that those of us who take another position in this very important and developing debate aren’t educated about plants, ecology, biology climate … well, that is assuming alot.

        • Hi Ivette,

          I really could not have more fun stuck in bed. And am loving these debates.

          I don’t see an “exotic vs native” debate here. That’s a nuanced conversation that is thankfully happening all over the place finally. I personally think that anyone who could look at a Magnolia soulangeana and not swoon a little probably shouldn’t be a gardener (and might not have a heart). Gardens are designed by definition and those of use inclined to design better be receptive to beauty.

          But as we learn more about plants as living organisms, rather than ornamental objects, it behooves the entire planet for us to start designing in a less environmentally destructive manner. And most people seem to be on board with that to some degree (I’d hope every single poster on here would agree).

          I in no way mean to insinuate that anyone who picks an exotic plant to plant is a jerk. But people who knowingly plant invasives? As far as I can tell, there are two options: either they don’t know what they’re doing, or they know and don’t care. I’d rather think people are uninformed than dismissive. But the author and many posters seem to find regulations secondary to their own personal opinions, even in regards to plants that are clearly harmful. Thoughts?

        • I think most folks do NOT understand or have much idea about ecology in gardens — folks not reading this post, for example, but who every spring go to Home Depot to pick up whatever strikes their fancy (and I’m not condemning weekend gardeners, how CAN they know? Esp when what’s for sale is often not native and sometimes invasive). I believe in native plants, we need a hell of a lot more of them in our landscapes. Period.

  7. Thanks for this great article. In my yard, I have burning bush that I never planted taking over the woods. These are non-native invasives, I can agree, and they are banned for sale in my state of Massachusetts. I also have Rudbeckia that are natives that exhibit invasive traits. The term for a native plant’s spread is called naturalizing, but the behavior is similar. In my yard the non-native is causing more trouble, but the native, in my mind, can also be invasive. I think that it is a matter of altered habitat, as Phytophactor says. I also agree with M. Willburn’s post.
    Thanks for the chance to debate this.

  8. I still think the term invasive applies only to non-native (what ever that is) plants with an aggressive and/or displacive/disruptive growth pattern

    and “aggressive” can be be used for native (what ever that is) plants with an aggressive/and or displacive/disruptive growth pattern

    There are native plants that are not aggressive
    There are native plants that are aggressive

    There are non-native plants that are not aggressive
    There are non-native plants that are aggressive – These and these alone are “invasive”

    • Yes! The difference between aggressive natives and aggressive nonnatives is significant. The latter can totally swamp a piece of land and crowd out everything else, and some plants can change conditions so that natives can’t come back by themselves. For instance, blue gum eucalyptus in the SF bay area sucks up all the water and also produces so much litter that virtually nothing grows under an old stand. If the trees are cut down and nothing more is done to try to restore the land, eucs will come back in force. French broom and related invasives in the pea family can add nitrogen to the soil, making it less hospitable to the natives that were there before. Whole hillsides have been totally covered with broom.

      In the wild, aggressive natives are limited and won’t take over an ecosystem; their “aggressiveness” is limited to a small garden setting. And in a garden, as noted, that’s called “fills in quickly” or “spread easily,” not “invasive.”

      • The removal of non-native forests in the Bay Area is heartbreaking, in my opinion. The re-creation of wind-swept dunes around the Bay Cities seems very simpleminded to me. Consider what the impact will be when all non-native trees are gone. It seems very bleak to me, but hey – there will be LOTS of nitrogen fixed in the soil. Of course, it will be too windy to grow much of anything with that optimal nitrogen balance – but I guess that will have to be a lesson learned.

      • There is a great deal of evidence that eucalyptus is not invasive: (1) aerial photographs of open spaces taken over 60 years show that eucalyptus forests have not spread; (2) Marcel Rejmanik’s article in Daniel Simberloff’s Encyclopedia of Biological Invasions reports that eucalyptus is not invasive. Both of these academics are well known invasion biologists who are perfectly willing to call plants invasive when they are; (3) The US Forest Service plant on-line database says that eucalyptus does not spread into wildlands.

        There is also a great deal of empirical evidence that the eucalyptus forest is as biologically diverse as native oak woodland and more biologically diverse than native redwood forest. See Dov Sax, Robert Stebbins, and Joe McBride; all academics at major American universities.

        There are also many documented cases of eucalyptus forests in which rare native species have thrived for over 100 years: endangered pallid manzanita in the East Bay hills; rare Pacific reed grass on Mount Davidson in San Francisco, etc.

        When eucalypts in the San Francisco Bay Area are destroyed, their stumps are sprayed repeatedly with herbicides to prevent them from resprouting. That’s one of many reasons why people object to their destruction. In exchange for a tree that is performing many valuable ecological functions, our public lands are being doused with herbicides. When the trees are destroyed the land is eventually occupied by non-native annual grasses and other hardy non-native plants such as thistles and broom. A native landscape is not the result of this pointless destruction.

        Native plant advocates in this comment thread say that those who defend harmless non-native species are uninformed, irresponsible, etc. Their condescending attitude is unsupported by the facts.

  9. Great rant! I think this is a case of a single descriptive word not being sufficient. I know we like nice labels and simple categories for everything, but it’s not always possible.

    Speaking of possible… there’s no plant that is truly impossible to control in a garden — even running bamboo. My neighbors can attest to that.

    • “even running bamboo. My neighbors can attest to that.”

      Not my neighbors, well one particular neighbor who died before the bamboo outran the barrier he placed just where he planted the plants, next to the property line. The problem was the roots grew along property line until they ran out of barrier and then into my yard. Growing into the path used by the gas and electric company employees who read the meters.

      I spent the last two summer digging a trench and creating a barrier along the much of property line (about sixty feet). I also dug up the path to pull out all the bamboo roots I could find, and covered it is multiple layers of weed block before covering it with pea gravel and pavers.

      Fortunately the new neighbors have no fondness for the bamboo, and may try to remove it. Though right now they are concentrating on the English ivy that my late neighbor planted in the rockery that borders my rockery. Which I have been trying to keep out of my rockery and yard for years. I even let them use my yard waste container when theirs became full.

  10. Susan, I’m with you and this topic is near and dear to my heart. I believe the word “invasive” shouldn’t be bandied about because it’s too important. We gardeners should be terrified of truly invasive species, whatever they happen to be in our neighborhood. But just because something grows (or self-sows) vigorously, enthusiastically, generously! doesn’t necessarily mean it’s a monster. Not if you have strength in your paws to edit out (share, redistribute, compost) the unwanted bits.

  11. Nandina is spread by fruit/seed and it is invasive. It pops up on our farm and we don’t have it planted anywhere. So is Spirea japonica (not on our farm but go up to the Smoky’s and it’s everywhere), and then there’s Cottoneaster. Lets not forget the next bush honeysuckle – Burning Bush it is every where! And the ever debated Butterfly Bush – first time I notice it was a solid road side drift almost 1 mile long near Chimney Rock, NC about 8 years ago. So the rant is somewhat factual but not completely.

  12. I agree with several of the comments above. My understanding of “invasive” is that an invasive plant is a non-native plant that displaces native plants or negatively changes the ecology of a habitat or plant community. This is the real concern. We’re talking native plant communities, it has nothing to do with a plant’s behavior in your garden. So the word should be used in context.

    I think promoting native plants is great, but there are still many great landscape plants that have been introduced that are not invasive. To avoid confusion when referring to plants in the garden I try not to even use the word invasive, unless I’m actually talking about them escaping cultivation. I use “aggresive” or “garden-thug”, and yes there are plenty of native plants that behave this way in the garden. It’s interesting to note that many invasive plants behave in quite the same way in their native environments, it’s not as simple as they lack natural enemies where they have been introduced.

    You are correct that there are regional differences, where one plant is invasive in one region and is not invasive in another. However, invasiveness in one region means it could be potentially invasive in another region, and we often respond too late. For example: Tamarix is probably only going to be invasive in the western U.S. where it invades riparian areas, changes the water table, and is very difficult to control. Barberry is a problem in the eastern U.S. It’s just barely on the radar in the midwest, so they plant them, by the thousands! It will be a problem in the midwest and by the time anyone does anything about it, it will be too late. How should we respond? This is a discussion we need to have.

    I think the horticulture world is really failing to lead here. The pushback is fueled by ideology (native vs. non-native, we can’d budge) and money instead of actual science. What do you know? Politics, right here on Garden Rant 😉

  13. From the PlantRight website
    Impacts of Invasive Plants
    Most of the plants used in gardens and landscaping do not invade or harm wildland areas. But a few vigorous species can — and do — escape into open landscapes and cause a variety of ecological problems. They displace native plants and wildlife, increase wildfire and flood danger, clog valuable waterways, degrade recreational opportunities, and destroy productive range and timber lands.
    When an aggressive plant is introduced to a new environment, the predators that would normally limit their growth in their home environment may not be present. This allows them to proliferate, spread, and take over natural habitats.
    Invasive species are one of the greatest threats to biodiversity worldwide, second only to habitat destruction. And the economic cost is as significant as the ecological cost: in California, more than $80 million goes to fighting invasive plants every year. A much-cited paper by Cornell researchers estimates the economic impacts of invasive species to be $120 billion a year. If divided equally through the 50 states, the cost to each state averages $2.4 billion annually — and given California’s size and resources, the actual impact is likely greater.
    It is widely agreed that prevention is the most effective and resource-efficient way to combat the spread of invasive plants. Please visit our pages for home gardeners and for nursery professionals to learn more about how you can prevent the spread of invasive garden plants.

    • A hosta is not native, but its ecological benefit pales in comparison to say zigzag goldenrod — which attracts more insect pollinators and is a larval host plant. So for me, hosta is invasive in the most annoyingly ideological way for most folks.

  14. Why does there seem to be this assumption that INVASIVE NATIVE plants can do no harm? What is that based on? Why do they get a pass? Any aggressive plant that crowds out the competition is by definition changing the ecosystem. What happens when INVASIVE NATIVE plants take over and smother the competition at a site where endangered plants and animals live? Is that just the way things are?

    I live with and do battle with INVASIVE NATIVE plants like Clematis virginiana, Symphyotrichum novae-angliae, Sambucus canadensis, Hydrangea arborescens, multiple Solidago species and the ever pleasant Blackberries to name a few. They all want to form monocultures and thickets at the expense of all else.

    When I remove all those thugs a whole range of diverse native plants show up. Don’t tell me INVASIVE NATIVE plants can do no harm.

    More to the general point of your rant Susan, I just don’t think there is going to be an easy terminology fix. It’s all too complex. There are to many factors and what ifs involved. I think people will just have to string together more descriptive words and be specific about what they mean.

    • 1. Native plants are not invasive. The fact that they are native means, by definition, they aren’t invading.
      2. Aggressive native plants are not “doing harm”: they are doing what they are supposed to be doing.
      3. If you think you have native monocultures, you probably don’t see the diversity that is really there.
      4. If you truly have native monocultures, you are doing something to cause it: they don’t exist in nature.

      • As I said in the post, natives are excluded from the term invasive by ONE of the several definitions – the political definition written by Congress, for purposes of allotting funds for removal.
        And I think the great harm caused by deer proves that natives can and do cause harm. If other factors change – development, killing off predators – nature’s plan for a particular species can go awry.

        • Susan, I’m willing to go out on a limb and assume you own a dictionary.

          If you look up the word “invasion” and ponder the definitions, I think you’ll be forced to conclude that you cannot invade your own home.

          Native plants, by their very definition, are from here. Therefore they cannot “invade” here any more than we can imagine someone invading their own home.

          And if the problem with deer overpopulation proves anything, it is that human activities often have unintended consequences.

          Just like human activities are accelerating climate change, human activities are fueling the deer overpopulation.

          That should be a cautionary tale against cavalierly messing around with plant communities, not an endorsement to do so.

        • Oh, I should add that I total agree that the concept of “invasive species” does not define all the possible ecosystem harms that humans can inflict.

          Our mismanagement, or failure to manage, ecosystems properly can lead to all sorts of problems like unnatural shifts in native plant communities.

          I don’t dispute that this is a problem. I do, think, it is a different problem.

          Either way, pretending as you do that the problem of “invasive species” is a made-up problem is unhelpful. As any article that begins by setting up a straw man is bound to be so.

      • ‘Native plants are not invasive. The fact that they are native means, by definition, they aren’t invading.’

        I think we need to also look closely at our definition of ‘Native’. A native plant that is native to a particular ecosystem and is then introduced to a different native ecosystem where it thrives without the checks of its native ecosystem can be called ‘Invasive’ whether a native or exotic it is introduced, it is not naturally occurring or currently occurring in that ecosystem.

        We are using the term ‘Native’ to generally?

        • I’d say that a plant introduced to an ecosystem is not native. The fact that it must be “introduced” tells us that this should be so.

          If I take a plant native to Arizona and plant it in Virginia, it is not “native” in the context of Virginia. It is an introduced species there and, if self-perpetuating and harmful, I’d call it invasive in Virginia.

  15. I find this article distressing. It’s an almost perfect examples of the sort of short sighted views that are at the root of many of our ecological problems.

    The author doesn’t like a term and doesn’t like the way that scientists, the government, and specialists are telling her she should define and use the plants she wants. She likes using plants ecologists tell her are invasive because she finds their invasive tendencies easier to care for in the garden. And she seems to think her *feelings* are somehow not only parallel but actually superior to the loads of scientific research and (minimal) government policy on the topic.

    As other educated posters have stated, there are actually very solid terms to deal with the easily solvable aspect of the article. There are:
    Exotic plants
    Invasive plants
    Native plants
    Aggressive natives

    • Yeah, Rebecca, but the point of the post is that many people don’t distinguish between your first two terms. The comments in this thread bear this out. People who use “invasive” and “exotic” (or “non-native”) interchangeably allow garbled use of language to produce garbled thinking.

      You seem to think that “scientists” support are telling Susan she should use native plants, not non-native plants. They aren’t. I encourage you to read modern papers on “invasion biology.” The field is collapsing because many of its assumptions haven’t been supported by evidence on the ground.

      • Hi Skeptic,

        Point 1) Agreed. It seems like a lot of people are confused about natives and exotics. Interestingly, rather than a “let’s define our terms, and here they are” approach, the confusion here seems mostly based around the official doctrine of the “Cult of Natives.” As an occasional preacher (and admitted strayer), I think the Cult is pretty clear on terminology. As for the overall message, I almost never hear anyone get all “ALL NATIVES ALL THE TIME OR YOU’RE A JERK.” Generally I think of it as “Hey everyone, maybe we should try to do something to counteract horticulture’s embarrassing legacy of environmental destruction and incorporate more plants that provide an ecological benefit to our landscapes. Invasive plants are no longer appropriate.”

        Point 2) I’m well versed on invasion biology, thanks. I’m also well versed in restoration ecology and of course permaculture (our competing cult). I assure you, David Theodropoulos is not blowing my mind or any actual scientific disciplines, if that’s what you’re insinuating. If that’s not where you were going, my sincerest apologies.

        The techniques and goals of restoration ecology are certainly worth debating, but I don’t think that’s what we’re really talking about on this thread, no?

        If you’d like to have yea ol’ native vs exotic plants benefit to wildlife debate, we can duel papers. But I’m not sure that’s what we’re talking about here either.

        This is about the continued use of known invasive plants in homeowner gardening. To which I say, “not ok!” And to which others seem to feel “it depends on how I happen to feel and my personal opinions.”


        • Theodouropolis is not a scientist and therefore doesn’t publish scientific papers. I had in mind papers like: Jeschke, Jonathan, et. al., “Support for major hypotheses in invasion biology is uneven and declining,” NeoBiota, 14: 1-20 (2012) And this paper grossly underestimates the problem that “invasion biologists” have supporting their key hypotheses: Most such studies are conducted by true believers, and negative results don’t get published.

          • Oh, you understand the paper and I don’t? As I said: the paper says that many studies have tried and failed to verify the core assumptions of “invasion biology.” The more studies, the more failure to confirm those assumptions. What do you think it says?

          • In case anyone is confused by these radically different perceptions, let me add a dose of reality. I have read this study. The study is accurately summarized by its title: “Support for major hypotheses of invasion biology is uneven and declining.”

  16. As gardeners, we mess with plant populations for a desired effect. Some plants are aggressive and some are not. Both traits are useful to gardeners for various reasons or purposes. When an aggressive non-native escapes into native ecosystems, it is classified as invasive for that region. No other plants should be labeled as invasive–aggressive maybe, but not invasive. I consider many plants native to my region as weeds and remove them for my own reasons, but the reason for their weediness is my desire for an artificial landscape, such as an edible garden.

    Humans have caused many natives to wander more widely than in unmolested habitats. If a plant is invading roadside ditches, this is a man-made habitat that would not exist without our presence. A case could be made that humans are the most invasive species.

  17. Well, I’m not about to address the terminology issue here (something else that everyone seems to have their own definition of), but at the risk of honking off any landscapers at this site, I will say that I’ve long felt that landscapers are a significant part of this whole problem. Most commercial installations where I live will have several DOZEN plants such as barberry or burning bush present – well, no bloody wonder these plants are taking over. I maintain with respect that it’s not often the home gardener’s fault – it’s the sheer numbers that landscapers put in that bears some blame here. Moderation in all things…..

    • Isn’t terminology the point of this rant?

      There’s little confusion over what “invasive species” refers to in the scientific community, and the term isn’t limited to just plants. Let’s take a few examples most people are familiar with: European Buckthorn, Garlic Mustard, Japanese Barberry, Oriental Bittersweet. While the specifics of invasion biology can be debated, the fact that these plants are not even native to North America, cause great ecological harm, and are very expensive to control, is not debatable. No gardener in their right mind would plant these, yet this is how they were originally introduced, before we knew better. Lumping them in with aggressive native plants, is a poor attempt to minimize the harm these plants cause. Using invasive as a synonym for all non-natives is just as incorrect. These plants are in a class by themselves.

      So if the problem is with the word “invasive”, what should we call them?

  18. A great article! I agree with one of your commenters about “The Cult of the Native”. People in gardening circles bow down to this concept over and over and it is very frustrating, as you noted, that natives can be invasive as well. It all depends on location, and it was brought home to me on my blog ‘The Garden Diaries’. I have a lot of Australian readers of my blog and mentioned Lantana as a great annual that tolerates heat and attracts pollinators in the mid-Atlantic region. You could hear the howls of protest as soon as I posted with lots of comments about the invasiveness of this plant in Australia! So, just like in Real Estate, location, location, location!

    • Can we please stop being so navel gazing in our plant choices? We need more selfless gardening, gardening that connects us to place and to other species — a holistic gardening that heals the rift between our marauding species and other lifeforms that have much to teach us about being alive in place. Garden for other life — butterflies, wasps, bees, flies, birds; yes this often, but not always, implies gardening with native plants whose blooms, leaves, bloom times, ultarviolet petal runways, etc are in evolutionary sync with native insect species.

  19. There is no question that the word “invasive” is overused. Here in California, that word is used to justify huge projects that are destroying hundreds of thousands of non-native trees that have been here for over 100 years. There is a great deal of photographic evidence that those trees have not spread, yet they are labeled “invasive” solely because they aren’t native. In the case of the Monterey pine, it is being eradicated only 100 miles away from its native range and there is fossil evidence that it existed in the past in the places where it is now being destroyed.

    In contrast, one of our ubiquitous native plants, coyote brush, has invaded grassland. This is more appropriately described as “natural succession.” However, many who wish to freeze-frame our landscape to a simulacrum of their pre-settlement fantasy are also advocating for prescribed burns and other artificial means of preventing this succession.

    Those who claim that there is no scientific basis for objecting to the eradication of the non-native landscape aren’t doing their homework. The scientific literature abounds that reports that the non-native landscape is performing valuable ecological services. Furthermore, the harmful methods used to eradicate the existing landscape, such as spraying our public open spaces with huge quantities of toxic herbicide, are doing far more damage than any non-native plant is doing.

    Thank you for this excellent article and for your courage in entering an emotional debate that has been largely devoid of empirical evidence.

  20. Since this post is addressing the problem with words, I’d like to point out the politics of the words chosen to identify plants:

    Invasive (invaders)

    Does anyone else find these words to be problematic – words that automatically engender a jingoism within the hort community? This is Xenophobia – and to me, the dialog comes very close to the rhetoric surrounding the “Illegal Alien” issues in our country.
    Everything comes from somewhere. Things move in nature, and are moved by various vectors. Some of those do damage where they land, others can thrive and benefit. The hand of man makes a process that would normally take hundreds of years happen much much more quickly, and yes, when damage is done it is BAD – but to over correct is not the answer. We (man) can’t be taken out of the equation – we are in fact, the solution. A solution can begin with language that doesn’t come loaded with political references – whether or not we are aware, we begin lining up and forming opposing sides, when in fact the solution is almost assuredly somewhere in between.

    Thank you, Susan, for this post – it was illuminating and brave. There is alot to think about here, and I am going to continue thinking. I know enough to know that my knowledge and education is incomplete … the more I learn in discussion, reading, and being in the field, the more my opinion will modify. I mistrust fixed opinions that seem to have no room for other points of view, and I will strive to let information from all sides inform my outlook on this matter.

    GREAT POST!!!!!

  21. Here in Oregon, scotch broom is spreading like wildfire, buddleia is not far behind. I see it growing along the freeways and in vacant lots and sidewalks.
    Yet it’s still sold and planted by many. English Ivy here is very invasive and consumes entire trees and hillsides. Finally killing the last of it in my garden.

    I’ve got lots of non native plants in my garden, but understand what it means to research the effect and costs (both of purchasing and of chasing what gets away from us) when I buy new plants.

  22. As you mentioned, what is invasive in one place – i.e. takes over and displaces what was there before – is a good citizen somewhere else. In New England, spirea and miscanthus are great garden plants. Here in western North Carolina, they have taken over roadway slopes and other sunny areas that are not being mowed. It seems that anything that can take hold here will happily spread all over the place, unlike the less gentle habitats of the northeast

    Ironically, we have miles of rhododendron that moved in to replace the native forests after they were clear cut. Their shade is so dense that not much will grow under them – rhododendron thickets form monocultures for acres and acres Invasive? I think so. Do I dare say that very loudly? No.

    • I’ve seen all that miscanthus along the road banks in N.C. and I’ve concluded that the real problem there is not the miscanthus, but the bulldozers that cut roads through the native forest.
      Many of the plants we claim are invasive are usually only invasive in disturbed areas. Buddleia is a good example. The problem is the disturbance. Intact, pristine natural habitats are rarely troubled by invasive plants.
      I suspect that the New England barberry problem is directly related to the New England deer problem.

      • Hi David,

        Are you familiar with Duke Farms in NJ? They have this incredible restored meadow that is absolutely filled with Miscanthus. It’s not the side of the road, this is one of the most sophisticated ecological/ornamental areas in the northeast.

        Human disturbance is certainly a HUGE factor with invasives: plants, animals, diseases, we’re behind a lot of it. However, there are plenty of examples of invasives that will penetrate intact ecosystems, and many that were specifically brought to our continent via ornamental horticulture. We have a long history of irresponsible behaviour to atone for.

        Lastly, if the invasive plants were here in the first place, they wouldn’t be able to take such advantage of our many disturbances, right? There are plenty of native early successional plants that would be more than happy to colonize your roadsides, but they’re outcompeted by the invasives.

        • But Rebecca, if its a restored meadow then its a disturbed site, right?
          And, I don’t think I can engage you in the debate that if we didn’t bring plants to this continent than they wouldn’t be invasive… we are humans and humans migrate and we bring stuff with us – especially plants. (and it may actually be the “intent” of nature for us to do that.) So, of course, if there were no humans on North America then this wouldn’t be a debate at all.
          I am as nostalgic for our original landscapes and plants as anyone, but I am a pragmatist. I think the debate about native vs. invasive is really not a about that at all – but rather an awareness of our culpability as people that is elevated by our observations as gardeners.
          You use the words “plenty” and “many” to describe the number of invasive plants introduced by ornamental horticulture, but its my contention that only a very scant percentage of the myriad number of ornamental plants introduced to North American gardens have proven to be truly invasive.

          • “J.B. Duke transformed more than 2,000 acres of farmland and woodlots into an extraordinary landscape. He excavated nine lakes, constructed some 45 buildings, and built nearly 2 ½ miles of stone walls and more than 18 miles of roadway.”
            I’m saying… This is certainly not nature. Its a big ass garden!! Mr. Duke probably planted the Miscanthus himself!!

          • Hi again David,

            Can you clarify one thing for me: is it your contention that, in any site ever touched by man, it’s somehow just fine for these invasive plants to be taking over? I’ll give you continual disturbance and the problems we create through poor land management. But when you have one plant dominate a landscape managed by top notch ecologists, to say that it’s a land management problem does not make sense. By that logic practically every inch of the country is fine for Miscanthus to invade, no?

            Point 2: once you start going down the “inevitability of invasion” pathway, you really get fatalistic. This is the same logic that allows people to rationalize driving Hummers (oil’s going to get used at some point, right?). The speed with which we North American’s have imported invasive species in the last few hundred years pales in comparison to any possible natural progression out there, and far surpasses any ecosystem’s ability to adapt or recuperate.

            I think we both agree that we’d like for our continent to be as ecologically healthy as possible, right? We’d love for wildlife to have the habitat they need and for our plants to grow as they desire. We’d love for the natural migrations and evolutionary processes that were taking place prior to colonization to continue.

            When you look at the overall number of plants imported, and the number of plants deemed invasive, certainly the ratio is a very large number to a comparatively small one. But that’s like saying you’ve got a very very good chance at winning Russian Roulette, so it’s no big deal to play. Just one wrong species can cause so much damage, why do we risk it if our goal is the above? Do the benefits really justify the costs?

            Cultivars of Purple Loosestrife and Callery Pear were thought sterile for years before they started hybridizing and invading. And even then, people have to recognize that invasive tendency, prove it with research, and then there’s an incredibly long process to getting those plants regulated, many states aren’t even there yet. There are many species in NY that are starting to invade, but we can’t even get barberry prohibited because of industry pressure.

            In the face of this incredible risk and complexity, I just don’t understand how gardeners would do anything but try in earnest to figure out the best strategies for ecological improvement, and stick to them.

        • Oh, and, as for the daylily debate from further up the post – yes – those daylilies were planted initially by gardeners who grubbed them out of their gardens because they had too many and then thrown in the ditches for erosion control. It was the common practice of old ladies when I was a child in rural Tennessee…
          And since those ditches were created by the DOT rather than God I don’t have a problem with it a bit and, in fact, love those long avenues of orange lilies lining the rural roads of the south. They are part of our cultural heritage.
          Unfortunately, now most counties around here have taken to spraying broad leaf weed killer on the roadsides so the daylilies (and everything that isn’t a grass) are all but gone.
          Of course those daylilies did eventually, in some areas, wash down into marshes and swamps and start to colonize. Back then, nobody cared about marshes and swamps so it wasn’t a problem. Now, of course, we better understand the value of wetlands and the value for their protection, so we are evolving our understanding, our knowledge and our actions.
          That evolution is the solution to this debate. We don’t have to be hysterical and condemn every gardener to hell for planting garden plants.
          Gardening is fashionable and the fashion of the day is to be environmental in our gardening practices and that trend should help us to moderate our behavior.
          And moderation means planting a daylily behind the garage is probably ok as long as the garage isn’t near a marsh!

          • Ok, this is my last post of the night. While I’m sure many daylilies were planted on purpose, I assure you the extent of their invasion is not due entirely to the good intentions of old ladies and then their subsequent downriver spread. Daylilies also invade many other sunny sites, meadows among them. You must have seen this happen, no? Or read about it? They form these dense mats and spread out.

            You might think it’s harmless to plant it behind your house, and then you move or age and it stops being managed. It spreads, it invades. This is how these things happen. It’s the good intentions of good people that do the most harm. Given the work involved in invasive species designation, it is literally the very least anyone can do to help the environment to avoid those plants that finally made it on the list. Literally, this would be the absolute least a person could do. And yet still, here we are. Debating baby steps.

          • As a point of clarification, what I’m saying is that if the site has already been transformed from natural to man-made then it is irrelevant whether non-native invasives are taking it over because it is no longer a natural habitat and what was there is already lost. The cat’s out of the bag. The miscanthus on the roadside is not the problem. The problem is the ROAD!
            Is it important that we plant broom sedge and sumac around every Target and McDonalds parking lot? Is that accomplishing some noble goal of restoring nature?
            And with your last assertion, aren’t you saying that we should absolutely not be gardening at all because we never know when our efforts will turn evil and destroy the world?
            Is it really the intentions of good people that do the most harm or are we, as gardeners, really low on the scale of wrong-doers? The large corporations with smoke stacks and coal mining and nuclear waste are no worse than Mable and her Geraniums?
            I participate in this site because its about gardening – something that I am passionate about and love dearly. Its my life’s thing.
            Every time I take a look on here I mostly see a bunch of people condemning people for gardening!! or at least condemning people for the way they garden and what they plant, etc.
            Yes, we could all be more thoughtful about our choices. I am, and I wish others would be too – but at the end of the day this is much ado about nothing.
            If you want to save the environment send money to The Nature Conservancy. But you and your neighbors and your city and your society need you to plant something pretty so we can all have a respite from the horror and disappointment and ugliness of the world we’ve made and be reminded that simple acts can transform.
            We are all right here, except when we condemn.

  23. Yikes,

    I see nothing has changed over at the ol’ rant. It’s been awhile, what more can I add. Criminy -it’s like Climate Change in here. Feel’s hot. Better go outside and pull out those damn daylily.

    Final thought: -whether it’s your fault or mine, we’re gonna go down together. Everyone kiss and make up.

  24. Ah, Susan! You always know how to whip the readers into a frenzy!

    So after reading over these comments (mostly), what sticks in my mind most is that because of previous climate change, nothing is native to its current region. Plants have constantly moved and adapted and evolved in response to the limits imposed on them by changing conditions. Once upon a time, redwoods were native to Alaska. Not anymore, and no one is demanding that we try to re-establish them there. Facing climate change in the coming years, are we going to hold on to “native” plants that grew in a particular area just because the conditions used to be perfect for them? At what point do we give in to climate change & say that what was once non-native & non-invasive is now native? How many generations? Seems to me that those arguing that non-native = invasive aren’t seeing that, digging far enough into our ancestry, none of us originated where we are. All life on this planet migrated from another place & was non-native at some point. Heck, even the rocks have been known to move around.

  25. Thanks, Susan!

    There’s been a whole lot of parsing about invasives but it seems to me that they are here to stay, unless someone takes action. Even the Dalai Lama acknowledged that prayer won’t get it done, and he prays a lot! Action is required, he says.

    I’ve been in Hawaii for 10 days and, beautiful as it it is, it’s also loaded with invasives, first brought by the Polynesians and on it goes. The threat continues with every plane and ship that lands today. Here’s a recent New York Times story about someone who is stepping-up to remove invasives on Oahu, one unwelcome tree at a time, with the help of committed volunteers.

  26. I think one of the problems about this “debate” is that it is so personal, i.e., we gardeners have personal, aesthetic feelings about particular plants. Also, people in the “industry” have a livelihood dependent on popular tastes (even if not their own).
    It might help to think bigger and less personally about this. Gardening has been about nature, beauty, food, but now us gardeners have an opportunity to be a force for restoration, helping species – animal and plant – recover (as best they can) from environmental/habitat destruction.
    Haven’t read this book yet, but it sounds like a promising discussion of the big picture.

  27. I remember when I was a kid we had a large patch of beautiful orange daylilies growing by the side of the driveway, but the powers that be of our house yearly mowed them away, proclaiming them to be “weeds”. I loved them but they never were allowed to grow. When I grew up, I saved some starts of these very same flowers and took them to my own home where they now very beautifully line a fence row, with little care or upkeep required. Call them “weeds”, call them “invasive”, call them whatever you may, but to me they are things of beauty, appreciated by me and here with purpose. I have, at times, noticed tags on plants for sale prohibiting the propagation of other plants from the one being sold. I have wondered if the tag “invasive”, meaning something that grows freely and easily, is something corporate producers would like to wipe out, so that, like Monsanto and seed production, they could strive to control the markets and reap profits from any plants we may choose to own. In my opinion, humans are “invasive” species.

    • Very nicely said, Skye. I had a personal experience with daylilies too. I had the pleasure of living in San Francisco for nearly 30 years. It’s a great little city, but it’s an unforgiving place to garden. I had daylilies in my front garden the entire time we lived there. They never failed me and they never spread anywhere. They were about the only thing in my garden that rewarded me every year we were there with their warm colors which are particularly welcome on the gray, foggy days of summer in San Francisco.

  28. After the discussion on this topic has come to an end – at least for the time being – what do all of you intend to tell your readers/followers/weekend gardeners who have no time for or interest in the nitty gritties associated with this issue?
    Unsuspecting, uninformed gardeners ought to know the consequences of purchasing plants that might be invasive or aggressive in their particular growing zones or that are predicted to “invade” their flower beds because they spread beyond the ability of small plot gardeners to control them. For many garden enthusiasts – and we must not ignore them because they keep the wheels of our industry spinning – the words, invasive, spreading, aggressive, non-native, and native can be overwhelming as well as an abstract distraction.

    Perhaps, in addition to height, spread, sun/shade, and growing zone, plant tags ought to inform the consumer how a specific plant will behave in one’s climate.

    • The problem with providing that kind of information is that a plant might be fast spreading under certain site specific or climate specific conditions and not at all in others.
      In our area almost all of the independent retain nurseries are gone leaving customers with no one to ask for reasonable first-hand advice and looking for information online is fraught with inconsistencies and misinformation. (And disagreement, as evidenced here!)
      The generic plant tags provided by growers and liner producers are also often used as a sales tool only and don’t come with warnings about the plant’s down sides. It would, for instance, be useful to know that Euphorbias, while great garden plants, cause contact dermatitis if you break the foliage or stems.
      Also, I wouldn’t necessarily want someone to avoid a plant because its fast spreading – that’s a good trait for people with large areas to fill or amateur gardeners who will feel more successful if the plants in their gardens are thriving.
      AND, after 20 years in my garden, I have come to find that some plants can be fast spreading the first few years and then mysteriously slow to a crawl as the garden matures. It would be hard to explain that to novice gardeners.
      As for specifically calling a plant “native” I think that does more harm than good. I would rather plants be promoted on their merits of garden-worthiness whether they are native or not. Often the plants sold as native are less satisfying to average gardeners which end up shying away from native plants in the future. Better for gardeners to want to build on past success by seeking out similar plants than to prejudice them against natives altogether.
      I’m offering this insight from my observations as a nurseryman and designer – not intending to reignite a feud!

  29. David mcMullin, I am intrigued by the line “some plants can be fast spreading the first few years and then mysteriously slow to a crawl as the garden matures”. Sounds like it would make an ideal topic for a garden blog post or gardening magazine article.

  30. Allan, I’m not sure that my observations can be substantiated… I’ve only noticed that in my 20 year old garden there have been plants that, early on, really took advantage of the open space and freshly turned soil. Some of those, like Eomecon and Tetrapanax, were starting to be pretty scary in that they popped up everywhere. Others, like Adenophora and Alstromeria made big clumps.
    Eventually I applied neglect as a gardening strategy and began to watch nature take its course and over the last few years have noticed that there is hardly any eomecon or Tetrapanax left in the garden and the big clumpers have been pushed back by maturing woodies.
    I suspect that the really fast spreaders quit spreading so much when I quit disturbing the soil by digging and topdressing and the competition from bigger woodies during times of severe drought was too much for the herbaceous plants to handle.
    In other words, I have stepped back and let secession take its course.
    These and other observations from other places and gardens I’ve accumulated over the years have helped me to come to a less hysterical conclusion about “invasive” plants than the general consensus. My overall understanding is that a plant’s invasiveness will run its course and natural secession will mitigate the process. Disturbed soil and degraded sites tend to promote invasiveness – but with time and less disturbance, those plants – which act like white blood cells – are no longer needed to repair the soil and they quit reproducing.
    The only exception that I see is in wetlands where the soil disturbance is a constant and natural process… so any invasive plant is likely to proliferate.


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