New Hort Research that Gardeners Can Use, Second Edition

by Jeff Gillman, associate professor of horticulture at the University of Minnesota.  This is the second of his quarterly reports; the First Edition is right here. 

Do you remember taking tests in school?  Remember how anxious you were to confer with your friends after the test to see if they got the same answers you did.  This may shake your view of scientists a little, but that’s kind of what it’s like with scientists when new papers come out on topics that they’ve already written about or researched.  We’re always taught that scientists are cool, cautious individuals who value objectivity above all things.  We certainly try, but speaking for myself I can tell you that we’re also human and so are prone to human reactions.  When a new paper is published on something that I’ve worked on I get anxious before I read it because I hope these new results agree with my own.  And, while I go out of my way to present articles which reach conclusions different than my own, there’s something gratifying about reading a paper where other researchers have independently reached the same conclusions that I have.  It’s kinda like being able to say “I told you so”.  The reason I mention this is that the first two articles I’ve decided to present here both gave me that little “I told you so” feeling.

¹Compost Tea?  Not so much

Those of you who have read my books or my posts here know I’m not the biggest fan of compost tea, and the first article helps to justify my skepticism.  This article examined the effects of two compost teas (a homemade aerobically produced manure tea and the commercially available Efficient Microbes) on collard and spinach growth and the result was that, in general, these teas did not increase the yield of these plants. (There was one treatment where non-organic methods were used in combination with the commercial tea and showed a slight increase in yield, but this was only true in one of two years and was considered statistically insignificant).

Furthermore, this research looked at whether compost tea increased microbial activity in the soil and found that it didn’t.  I’m always a little surprised when people think that adding microbes to the soil will increase microbe activity.  It really shouldn’t.  Think of a thousand people taken from Boston and suddenly dropped into the middle of the Mojave Desert.  How many would remain after two weeks?  Living beings, whether human or microbial, will only proliferate where conditions are good for them to live.

²Mycorrhizal products?  Save your money

A commenter to my last research update asked about mycorrhizae and whether it’s a good idea to add them to your plants or soil.  I was concerned that I’d need to look up some old articles and post those until last week when this shiny new article about mycorrhizae found its way into my mailbox.  In this article researchers applied commercial mycorrhizal products (9 of them!) to various plants and discovered that, in most cases, these products do not increase the mycorrhizal colonization of plants they’re applied to.  (An insignificant 5% increase was about as good as it got).  Mycorrhizae are everywhere and so I’m not sure there’s a good reason to purchase them from a commercial source.

³Butterflies are choosy! 

If you’re planning on planting Zinnias, here’s a neat little article you’ll appreciate.  Butterflies preferred the cultivar ‘Lilliput’ better than 2:1 over any other cultivar of Zinnia tested.  (Other cultivars tested included ‘Oklahoma’, ‘State Fair’, and Pinwheel’.)

⁴What landscaping is worth

Readers probably realize that nice landscaping can help sell your home, but exactly how much extra is this nice landscaping worth to buyers?  Well, 75 homes in Lubbock, Texas were examined to determine how much and it turns out that a high quality landscape increases the sales price by 5.7 percent, compared to average landscapes.  Then comparing average landscapes with excellent ones, the difference in sale price is a whopping 10.8 %.  Furthermore, the authors calculate that every $1.00 spent on the landscape returns $1.35.  I’m obviously investing in the wrong place.

⁵Balled, burlapped and busted?

If you plant balled-and-burlapped (B&B) trees, a new study shows that handling and transporting them in that form is detrimental to their growth.  It also seems to contradict recent statements from some quarters that it isn’t important to keep the ball of soil around those B&B trees intact.  As a side note,  last spring I tried planting B&B trees after very carefully washing off the root ball and of the five trees I treated this way, all died.  The five trees I planted using more standard practices all lived.

⁶Plants are powerful things

If you’re visiting this blog then you know the power of plants to heal.  Nonetheless, here is a little article that I hope will brighten your day.  Patients that underwent surgical procedures and were placed into rooms with plants and flowers had shorter hospital stays, less pain, fatigue and anxiety, and liked their rooms better than those who didn’t have plants in their room. File this under “who would’ve guessed.”

Sources below the jump. Top photo from Blossom Creek Farm.  Lower by SSTUDIO.

¹Knewtson, S.J.B., J.J. Griffin, and E.E. Carey. 2009. Application of two microbial teas did not affect collard or spinach yield.  HortScience 44(1):73-78.

²Wiseman, P.E., K.H. Colvin, and C.E. Wells.  2009.  Performance of mycorrhizal products marketed for woody landscape plants.  Journal of Environmental Horticulture 27(1):41-50.

³Yeargan, K.V. and S.M. Colvin.  2009.  Butterfly feeding preference for four zinnia cultivars. Journal of Environmental Horticulture 27(1):37-41.

⁴Stigarll, A. and E. Elam.  2009.  Impact of improved landscape quality and tree cover on the price of single-family homes.  Journal of Environmental Horticulture 27(1):24-30.

⁵Koeser, A.K., J.R. Stewart, G.A. Bollero, D.G. Bullock, and D.K. Struve.  2009.  Impacts of handling and transport on the growth and survival of balled-and-burlapped trees.  HortScience 44(1):53-58.

⁶Park, S.H. and R.H. Mattson.  2009.  Therapeutic influences of plants in hospital rooms on surgical recovery.  HortScience 44(1):102-105.

Comments

[sarahammocks]

I'm very curious--what is a "high quality landscape" and what is an "average landscape"--as defined in Lubbock Texas?

[gardenrant]

Jeff, it's always a pleasure to read your stuff. I was totally convinced by the "rinse off the root ball" argument.

[thistleandthorn]

Great post, Susan. Thanks for sharing.

[Country Gardener]

Fascinating. Confirms my gut feeling that fussing with compost tea is a huge waste of time.

[Steve]

I'm curious about how the benefits of landscaping were calculated....were the percent increases calculated on a base of expenditures during the previous year? Previous five years? Also, were gardens included as landscape? My own experience (sigh) is that unless potential buyers are gardeners themselves, gardens = work, and don't increase the value.

[Holly Scoggins]

Jeff,
Thanks for the helpful Mojave Desert analogy. I've had this [delicate] conversation with compost tea enthusiasts; expressing that if the environment was right for sustaining microbial growth, they'd be there regardless. Though I completely understand their POV...all the steps and effort [tea ceremony?]does make it seem like the right thing to do.

[Tara Dillard]

Obviously the value of landscaping deserves an entire issue of articles in a magazine. Possibly its own magazine?

Most of my out-of-state landscape design work is from clients formerly living in my city. They credit their landscape with helping to sell their house. Enough to fly me to do it again.

A Scottish study confirmed a link between living in view of a landscape & longevity. Not gardening, simply living in view of a landscape. Brain dead at the moment about the name of the study.

Steve's comment is correct about potential buyers thinking gardens = work. I know getting the 'landscape designed' garden correct equals a quickly sold house.

If a home is 'landscaped' and the 'landscape' hurts the sale of the home the'landscape' was poorly done.

Another topic for a magazine article!

Garden & Be Well, XO Tara

[Ether Maiden]

Very interesting!

[Chris Mousseau]

I found all these points very interesting - but I'm really curious about the statement:
"As a side note, last spring I tried planting B&B trees after very carefully washing off the root ball and of the five trees I treated this way, all died. The five trees I planted using more standard practices all lived"

What are 'standard practices" - do you mean simply planting B&B without washing the rootball or is there something else involved?

[Jeff]

Hi Chris,

By washing off the root ball I mean that I washed most of the soil off of the root ball -- the tree ended up "bare-root". Standard practice is to plant the tree without removing the soil -- only as much of the cage and burlap as you can without disturbing the soil ball (it may be helpful to look at the picture of a B&B tree which Susan included here.

[Jeff Gillman]

Hi Sara,

Here's the basics "Landscape was evaluated on tree cover and quality, grass quality, volume and diversity of foundation plants, plant maintenance, concrete condition and size, amount of soft- and hardscapes, and design coordination." Based on these criteria scores were given -- If you're really interested you should look up this article -- it gets a little elaborate for me to explain in detail here.

[Jeff Gillman]

Hi Steve,

The authors spend pages talking about how they came up with these figures -- much too much for me to summarize appropriately here, so I recommend you take a look at the original article when you have the chance.

That said, the authors estimated that a landscape would need five years to reach maturity.

I do not believe that gardens were considered part of the landscape.

Sorry for the cop-out answer, but this wasn't a simple equation.

[arythrina]

Thanks very much for writing up summaries of research findings - this is how science progresses!

It's important to try lots of new and innovative techniques (such as compost tea) but then also subject them to randomized controlled trials. So keep the science coming!

[Jeff Gillman]

Well said!

Thanks,

Jeff

[Pam J.]

I thought the point of using compost tea was to increase the level of nutrients in the soil. No?

[Marie Viljoen]

Regarding ball and burlapped trees:

I design gardens for rooftops in New York City, mostly, and nearly all of the trees we use are BxB.

http://66squarefeet.blogspot.com/2008/08/something-for-shade.html

It is a very rare occasion when one does poorly. We keep the soil around the roots intact apart from some judicious "scratching"...

[Jeff Gillman]

People use compost tea for different things -- usually to increase microbe levels. If you're just using compost tea to add some nutrients then go for it -- it'll work.

[firefly]

Interesting thing about the B&B trees, as I've planted quite a few bareroot perennials in the past 2 years and nearly all of them survived.

On the other hand, shrubs and tree starts I've planted or moved, whose rootballs disintegrated during the process (not intentionally), pretty consistently didn't survive.

Wondering if dormant vs active (that is, did your trees have leaves, Jeff?) is the key? All the bareroots I received were dormant and were planted early in our season (mid- to late April, before last frost date).

[greg draiss]

Sense and sensibility has returned....
Thanks Jeff

The TROLL

[Jeff Gillman]

We did plant "in leaf" which makes for a tougher transplant. It is well known that transplants tend to be more successful if they're planted dormant. The trees we were planting were Turkish filberts about 1 3/4 inches in caliper.

[Ginny Stibolt]

But are the gardeners considered to be part of the landscape?? :-)

[Old Kim]

Plant doctors have my respect and I mostly agree with what they have to say. Never followed Linda Chalker Scott's advice on how to plant balled and burlapped specimans. Would never advise it. Washington State University
The Myth of Collapsing Root Balls
“Balled and burlapped root balls must be left intact during transplanting”
The Myth
While shopping for trees at my favorite nursery, we recently overheard another customer ask a staff
person about installing her newly purchased B&B tree. “When I plant my tree I should take off the burlap
and twine, right?” she asked. “Oh no,” exclaimed the staffer. “You don’t want to disturb the root ball.
Just peel the burlap back from the trunk and leave the rest intact. Otherwise, the root ball will collapse
and the tree will die.”
At first glance, this appears to be reasonable advice. Balled and burlapped, or B&B trees, are much
heavier than containerized plants and one can visualize the root ball collapsing and crushing the root
system. The weight of the root ball also helps stabilize the tree and prevent tilting or falling. Finally, the
root ball soil contains beneficial microbes and other soil organisms that can help ease transplant shock to
the root system. With these benefits in mind, why would you consider doing anything differently?
The Reality
Many nurseries will not guarantee their plant materials if the customer disturbs the root ball, so customers
are loathe to do anything that might negate this policy. This is unfortunate, as disturbing the root ball is
exactly what you want to do to maximize survival of your newly transplanted tree.
A previous column discussed how to transplant containerized plant materials properly, and some of the
same issues apply to B&B trees as well. The most important reason to disturb the root ball of a balled
and burlapped tree is to inspect the root system. The circling, girdling, kinked, and hooked root systems
often found in containerized plants occur frequently with B&B materials, too. Nearly every B&B tree I
have purchased and installed, either in my own landscape or as part of a project, has had serious root
defects. By removing the heavy clay one can find and correct many of these defects. Without corrective
pruning these defects will significantly lower the life span of your tree. Remember, root pruning
stimulates the growth and development of new roots that will enhance tree establishment in the landscape.
A second reason to break up the root ball is to remove the clay soil that makes the tree so heavy in the
first place. Most B&B trees are grown in a soil with clay characteristics so that when the tree is dug the
root ball it will hold its shape: sandy soil will simply fall away from the roots. The clay soil not only
maintains its shape but also retains water, so that B&B materials are usually more stable in terms of
optimal water conditions during the time they are out of the ground. When the tree is planted into the
landscape, however, the clay character of the soil is often different than that of the surrounding native
soil. Differences between soil textures will impede water movement and therefore inhibit root
establishment.
A final reason to remove the bagging materials and root ball soil is that many of the B&B specimens at
the nursery have been burlapped too high during field digging and bagging. Burlap and soil that covers
the trunk above the root crown will lead to trunk disease and death. In every nursery I’ve visited I have
found more than one tree trunk literally rotting in the bag. Before purchasing any B&B stock you should
ensure that a healthy trunk lives beneath the burlap.
The best practice for transplanting B&B trees is relatively straight-forward. (The rationale for many of
the practices listed below are detailed in previous B&B columns):
1) Remove all wire baskets, twine, and burlap from the root ball. Working on top of a tarp will
allow you to transport the root ball remnants elsewhere.
2) Remove all clay from the root ball. This can be done most easily by using a water bath or a
hose. Use your fingers to work out clumps of clay from between the roots.
3) Look for and prune out defects in your freshly denuded roots. Be sure to keep the roots moist
during this procedure and work in the shade if possible.
4) Dig the planting hole to be only as deep as the root system and at least twice as wide. The
hole will resemble a shallow bowl.
5) Form a soil mound in the center of the hole to support the root crown of the tree, and arrange
the roots radially.
6) Backfill with native soil; do not use any type of soil amendment.
7) Water in well, preferably using the water from step 2 which will contain nutrients and
microbes. Do not step on the root zone, but gently firm using your hands. Add an
appropriate fertilizer (i.e. primarily nitrogen and little or no phosphorus)
8) Mulch the entire planting region with at least 4” of organic mulch, keeping a buffer between
the trunk and the mulch to prevent disease.
9) Stake your tree low and loose with 3 stakes for no longer than one year after planting.
10) Keep your tree well watered during the first year of establishment. You may have removed a
good portion of the root system and its ability to take up water and nutrients will be
temporarily impaired. Do not succumb to the temptation to crown prune or add expensive,
but pointless, transplant supplements.
This method is radically different from historically accepted practices. Yet recent and ongoing research
demonstrates that bare-rooting B&B trees leads to substantial increases in tree establishment and survival.
Investing the time to prepare and install trees properly will pay future dividends of reduced maintenance
and mortality for the lifetime of your landscape.
The Bottom Line
• Balled and burlapped plant materials usually contain soil significantly different than that of the
transplant site.
• Differences in soil texture will impede both water movement and root establishment.
• Root defects can only be found and corrected if root ball soil is removed.
• Proper root preparation combined with best practices for installation will greatly improve tree
establishment and survival in any landscape.
For more information, please visit Dr. Chalker-Scott’s web page at http://www.theinformedgardener.com.

[Dan Eskelson]

I have used compost and manure teas since the late 60's - for vegetables, ornamentals and interestingly for disease suppression on golf course putting greens.

I was one of the first to develop a non-chemical approach to golf course management, and much of my success resulted from regular applications of home-brewed compost teas sprayed directly on turf. The "unnatural" culture required by the golf course environment puts incredible stress on the plants and normally requires huge chemical inputs. Almost all chemical input was unnecessary in this program.

Though current science may indicate otherwise, the efficacy of disease suppression with compost solutions was first pointed out to me by scientists in Germany, who have been successfully controlling phytophora and other fungal diseases with compost solutions.

I've seen excellent response from compost tea solutions for almost four decades. The proof is in the pudding.

[Beth Botts]

Jeff, I am very sad that my $129 oxygen-bubbling compost tea maker won't get me more soil microbes but relieved that at least it might get me some nutrients. A question: If the nutrients already made by microbes are the only useful part, does that mean I don't have to worry about applying my compost tea within 4 hours after I finish the bubbling? I can just let those microbes die off, because the tea will still contain the elemental nutrients they made, right?
I planted a B&B Canadian hemlock last September and despite assiduous watering through the fall it looks like a goner. I pulled back the burlap but didn't break up the root ball. I should have planted a smaller container one and skipped the B&B issue altogether.