Challenger of Orthodoxy


Kathy Purdy’s excellent post on zones cites author Peter Del Tredici on the subject, and that reminds us to tell you about a couple of his other articles, found in Landscape Architecture Magazine.  Del Tredici gets lots of attention for lots of reasons, including his 30 years at Harvard’s Arnold Arboretum, where he’s now director of its living collection and senior research scientist.   He also teaches at Harvard’s Graduate School of Design.

In this (PDF) article, "Plants are at Stake," the author speaks up for plants "because too many landscape architects undervalue them".  Apparently when he began teaching landscape architecture students at Harvard he expected them to lack plant knowledge but was still surprised by the low level of scientific understanding.  He emphasizes soils, microclimates, and even maintenance, a "dirty word" at the school.  "As a teacher, I tend to challenge the orthodoxy." He encourages students to make sure plants are suitable to the site and notes that native species haven’t exactly flourished in cities.  More on that touchy subject below.

In his controversial article "Brave New Ecology" – also in PDF – Del Tredici criticizes what he calls "faith-based" notions of restoration, which ignore ecological realities.  He says our goal should be sustainability, not "romantic notions of bringing back the past."  If you’re shocked by those notions or his acceptance of invasive plants, let us know in your comments.  And if you’re not shocked, why not?

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  1. This dovetails with a lot of what I have been reading over the past year on sustainable gardening and garden ecology, so I’m not shocked by what del Tredici says.

    He makes a very good point about humans changing conditions so that natives can’t adapt even if we want to bring them back, and that they’ll behave differently in an altered environment — although I did find myself asking why some soil remediation wouldn’t be on the plate if heavy equipment ruined things to the point that only a few plants would be appropriate to a site afterward. Loosening the soil and adding organic material would seem a ‘no-brainer’ part of the budget, something that would bring a nice return on investment, open up the palette of plants that could be used in the design, and assist in the maintenance phase.

    I’ve also come to think of ‘invasive’ as a relative, even behavioral, term. A lot of species can, given the right conditions, act aggressively and overcome their neighbors, even ‘natives’.

    These were excellent articles — thanks for posting the links.

    {As a very small side point, would it be possible to amend the post to add (pdf) next to the links? Some of us (me included) have browsers that automatically download these to the desktop rather than opening them with a plugin, so it would be nice to know what the link points to.}

  2. I’m not surprised to hear that design often trumps plants among landscape architects. You can see that in each issue of Garden Design magazine. Isn’t that kind of like Frank Lloyd Wright designing those award-winning buildings whose roofs promptly began to leak?

    I think it’s brilliant that Del Tredici takes his students on site to have them hear from maintenance workers. After all, a design will only do you so much good if the plants die afterward.

    One note: at least in Austin, native plants seems to thrive on green roofs and on city streets. Perhaps that’s because those harsh environments (hot and dry) are suitable for central Texas’s most drought-tolerant plants. I can see that if your native environment was cool, rainy woodland, your native plants might not survive on exposed roofs or city streets. It just depends on where you live.

  3. I think what Peter say’s dovetails with our philosophy at the nursery. We feel here in the foothills of California landscapes should be made up of predominately Mediterranean climate plants. While this includes natives we do not limit the landscape to only natives. This is the argument they have had in Placerville where the city govt. requires x amount of natives be planted in commercial landscapes. As stated in the article many natives do not perform well in altered soil resulting from construction.

    It would be better to plant natives and other plants from like climate regions that have been proven to perform in our unique area. South Africa, Australia, the Mediterranean region all have plants that can be used here. Most are drought tolerant which is a necessity where we have no summer rain.

    Invasives such as scotch broom, pampas grass, and other should not be planted despite their ability to grow well here. I agree with Peter that trying to recreate native habitats may in the long run prove fruitless. But we should when appropriate, but be prepared to “maintain” them indefinitely.

  4. Thanks for the post, Susan, and for the link to the fascinating article by Peter Del Tredici. I’m have no expert knowledge, but my only restoration experiences in Texas had problems for the reason Peter cited. At that time we lived in a house where deer roamed. The deer preferred the native plants, so the plants that belonged in that yard never reseeded or established themselves. It was discouraging and expensive. Combining native and introduced plants did help, with the Mediterranean Rosemary and Artemesia planted as guards around the natives.
    I’m in a different Austin subdivision now, and I still buy and use lots of native plants, but can’t imagine them ever being content with this soil, or being dependable enough be the mainstay of my landscape. I’m willing to keep planting natives, but know that it is futile to make absolute rules about their use.

    Annie at the Transplantable Rose

    [I’d like to second Firefly’s statement; it’s polite to warn someone whenever a link opens a pdf file. I like them, and they’re useful, but when my computer is taken by surprise it seems like kidnapping].

  5. Finally, I can post Gloria’s comment:

    I am surprised only by the persistence of some to try and discourage the use of natives. It is my opinion that native plants are often the best
    choice for a given purpose. Rather than return to some utopian past,moving into a future that requires our best efforts to deal with
    the changes taking place is the purpose.

    I live and garden in an urban area,quite successfully, with many native plants chosen for the specific site and purpose. Native plants are proving to increase the numbers of insects in an area which results in a biological control of pests (balance rather than an elimination).

    Local governments are concerned about storm water run off. Keeping rainfall at or near where it falls keeps the rainwater from the pollution of sewers,restores ground water levels, and slows the movement of run off into water ways thus preventing flash floods. Native plants with deep roots and a tolerance for intermittently wet soil are working well (in man made systems) to acheive these results.

    Even though non- natives have proven to work on roof top gardens with existing rainfall amounts,some chose to use a watering system on occassion and grow a more diverse group of plants so as to accomplish the dual purpose of encouraging wildlife and reducing heat islands.

    Of course using native plants in gardens changes the evolutional direction of the gene pool. Gardeners amend soil and water, which slows the developement of deep root systems and plant in areas protected somewhat from the harsh environment of the wild. This is why native diversity should be protected in the wild. I choose to follow a path that encourages diversity in thought and action as well as life. A light that shines from only one direction merely lengthens the shadow.

    Posted by: Gloria at Jan 20, 2007 12:29:06 PM

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