Garden seminar coming to a place near you?

I just got back from British Columbia where I spoke to 2 garden club/Master Gardener groups.  It’s always easy for me to do seminars in BC or along the west coast, but I rarely get a chance to go elsewhere.  Many times it’s the expense that keeps groups, especially garden clubs and nonprofits, from bringing in speakers.

So here’s my idea:  I keep a gift account budget here at WSU with the donations people make towards my educational program.  Occasionaly I’ll make an equipment purchase, but for the most part it’s intact.  And today it hit me – why not use it to help fund travel throughout the US (or elsewhere?) to give educational seminars? 

So before I go any further with this thought, maybe some of you can give me feedback.  Would your institution/garden club/or other group be interested in having me give a seminar on some aspect of sustainable urban horticulture?  Just post a reply in the comments with your general location.  I’ll see if there’s enough interest to pursue this further.  I’d probably try to organize this trip for sometime in late February-early March of 2011.

What’s old is new again

While the Emerald Ash Borer (EAB) continues to expand in the upper Midwest (see  for a current infestation map), EAB is old news here in Michigan, especially in the southeastern part of the state.  Efforts to restore urban and community forest canopy lost to EAB will continue, however, for the foreseeable future. In 2003 we established an Ash Alternative Arboretum MSU Tollgate Education Center in Novi, MI – which is near ‘Ground Zero’ for the EAB infestation in North America.


The planting offers some insights into selecting alternative landscape trees to replace ashes.  A couple of elm cultivars, in particular, have emerged as shining stars in the demonstration planting that includes five specimens of 37 different species and varieties.  All trees were planted as 1½”-2” bareroot liners by Tollgate volunteers.  Tollgate farm manager Roy Prentice has overseen the maintenance of the planting.


Accolade elm (Ulmus japonica × wilsoniana ‘Morton’)  Compared to most of the other selections planted in the arboretum at Tollgate, Accolade elm looks like a man among boys.  Growth of these trees has been outstanding – the trunks of the trees have grown fast enough that they have split off their plastic rabbit guards (see photo).  Like Triumph elm, Accolade elm has dark green glossy leaves and develops into a large tree.  Although elms are often thought of ‘ugly ducklings’, both Triumph and Accolade are quickly developing well-formed vase-like crowns.


Triumph elm (Ulmus ‘Morton Glossy’) has also done very well at the Tollgate planting.  This elm develops a vase-like crown with age and has dark green, glossy leaves.  A large tree to 55’.


The elms are part of series of elm cultivars that have been developed with high tolerance of Dutch elm disease.  Most of the new elms are hybrid crosses with Asian and European elm species, though selections of American elm that are tolerant of Dutch elm disease are also available in the nursery trade.  The irony in all of this, of course, is that native American elms were devastated by another introduced exotic pest, Dutch elm disease.  As elm trees were rapidly lost during the 1950’s, 60’s, and 70’s, ash trees became a popular replacement due to their ease of transplanting, growth rate, broad site tolerance and pest resistance (yet another irony).  Now we’re promoting elms to replace ashes.


Street scene before and after Dutch Elm Disease.  Photo:

The moral of the Dutch Elm Disease and Emerald Ash Borer stories is that it’s critical to avoid over-reliance on one species or even one genus – even a native one.  In Michigan some of our urban and community forests are over 50% maple.  As global trade increases and the potential for destructive pests to hitch-hike around the world rises, the best hedge against catastrophic tree loss is to plant a broad and diverse array of adapted trees.

Shear lunacy

I subscribe to Digger magazine, the industry publication from Oregon Association of Nurserymen.  I am always curious about trends in the nursery industry and this magazine is a good way to find out what home gardeners are buying.

The cover feature of the May 2010 issue is on topiary. While I can appreciate topiaries in formal gardens – with dozens of gardeners to keep them shaped up – I think they are poor choices for most home landscapes.  Shearing plants to maintain a particular size or shape is a never-ending activity that most homeowners will tire of quickly.  Nevertheless, the magazine reports that topiaries are becoming more popular for home landscapes, especially along the East Coast. The article showcases the newer topiary shapes – stars, crosses, angels, even cacti – in addition to the traditional spirals and poms.

The article warns growers that skilled employees are needed to prune topiaries properly, and that the time commitment to create and maintain topiaries is significant.  One grower states “it’ll take a fair amount of time to shape it, and then you’ll be trimming it lightly a couple of times a year until you sell it.”

Curiously, the article says nothing about either the time commitment or pruning skills needed for homeowners who purchase topiaries.

Even more curious…the subsequent issue of Digger is devoted to sustainability. Seems a bit of a disconnect there.



Plastic grass and organic gardens

One of the best cures for writers’ block for a Garden Professors is to spend a little time in front of the tube watching home gardening shows.  Now, to be sure, there are useful nuggets of information that can be gleamed from an hour or so of gardening or landscaping on HGTV or PBS Create.  But there are moments when I just stare at the TV in disbelief and go, ‘Have these people lost their frickin’ minds?’


A recent case in point, a half-hour gardening show devoted to installing an ‘allergy free’ backyard for a youngster, we’ll call him Billy, with environmental allergies.  Let me state up front I am in no way minimizing the seriousness of environmental and related allergies.  I suffer wicked seasonal allergies (yes, I know, poor career choice) and I have several close friends whose children have severe allergies.  I realize allergies can seriously affect quality of life and, in the cases of some food and insect allergies, can be a matter of life or death.  And I realize that a parent will do just about anything to keep their kid healthy.  Nevertheless, some of the practices promoted on this show strained all manner of credibility.


First, since Billy is allergic to grass, the landscaper replaced all of the grass in the backyard with synthetic turf.  Grass allergies are among the most common allergies but what is it about grass that most people are allergic to?  Pollen.  According the National Institutes of Health just keeping grass mowed is a simple preventative measure to reduce grass pollen.  Synthetic grass may have issues of its own with molds and there are remaining uncertainties regarding the safety of the used-tire derived crumb rubber used in some fake turf.   And if Billy has issues with pollen, I saw a much bigger problem looming like an 800 lb gorilla as the camera panned back from the picture-perfect synthetic lawn: Trees, specifically dozens of oaks and pines in the woodlots beyond the backyard.  I joined the show part way through but the overall landscape looked like the Southeast, perhaps Georgia or the Carolinas.  Even if the fake turf does reduce grass pollen in the back yard, Billy will scarcely notice as a yellow-green cloud of tree pollen envelops his house every spring.


Next, in addition to wanting a place to play, Billy wanted a vegetable garden.  Actually, given Billy’s obvious disinterest during this part of the show I don’t think he was really that interested in vegetables but the producers knew they couldn’t fill a 30 minute show with just fake turf.  Assuming Billy really was into vegetables the solution, of course, was an organic garden.  Why an organic garden is a panacea for allergy sufferers was never explained in the show; apparently pollens and molds don’t hang out in organic gardens.  The choice of vegetables was curious as well.  Billy got to plant squash and watermelons; guess no one bothered to tell Billy that cucurbit allergies are among the most common food allergies for people predisposed to pollen allergies.  For good measure, Billy got to plant some corn – doubt that could ever produce any pollen…


Bottom-line: take the info from the garden shows with a grain of salt and consider the source of the information.  Often times these shows are limited to whatever local source they could dredge up.  Do you really want to rely on a landscape contractor to make decisions about your child’s allergies and health?  Enjoy the shows but keep your skepticism handy and be ready to do some fact checking on your own.

Compost tea…again

My not-fan Justin has emailed me again with some more substantial comments of my criticisms of compost tea.  I’ve posted his email here, along with my responses in a point-counterpoint format:

1.  “Compost teas do vary from batch to batch, the same way galaxies vary.  Without the complexity and biodiversity present in the tea, you might as well just be using water.”

Yes, they do vary, and this is why it is so difficult to conduct replicated and repeatable studies on the efficacy of compost tea.  The comparison to variability in galaxies is really not relevant, nor is it conducive to experimentation.

2.  “Generally speaking though, this can be overcome by the purchase of virtually any microscope capable of achieving 400x field of vision or greater. By looking at what is present in the tea and a little bit of background knowledge, one can make an educated decision as to whether or not it will improve conditions on one’s plants and soil.”

Purchasing a microscope does not overcome variability.  Furthermore, microbial species can’t be reliably identified simply by looking at them under a microscope.  The “little bit of background knowledge” is vague.  What, exactly, will help in making the “educated decision” in whether it will do any good to use it?

3.  “I assume that these steps were not taken in these experiments, because of the generally lacking method in what has been come to be labeled (tobacco science).”

The steps referred to (I assume in point 2) are not useful in assessing efficacy of a product – in other words, demonstrating an effect not seen in the control treatment.  What would be the control?  Not looking under a microscope?  Not having background knowledge?  An experiment requires experimental variables.  I hadn’t heard of  “tobacco science” and had to look it up.  Apparently it’s “science that is skewed or biased, especially toward a particular industry.”  The only industry I see in this discussion is the compost tea industry – and yes, it’s an industry.

4.  “First of all you are trying to disprove compost tea as a foliar pesticide only. You do not do a relatively new science justice by not looking at the wholeness. Any and all foliar applied pesticides are palliative in nature, and symptoms will recur if you do not deal with the source problem. Compost tea (aerated) is to be used in the rhizosphere first, foliage second, and surrounding environment third. If you are not talking about this mode of application, you are not talking about compost tea.”

Compost tea is not a new science.  It is a product.  To demonstrate efficacy of a product requires conducting a controlled experiment in which there are one or a few variables.  It’s not possible for science to look at the “wholeness” of compost tea – it has to be looked at systematically.  Neither is compost tea defined by its mode of application.

I do agree with Justin, however, that symptoms (of disease or whatever) will recur if the underlying problem isn’t addressed.  There are scientifically testable, consistently reliable methods for improving soil health and plant health. At this point, compost tea is not one of them.

5.  “In order to disprove compost tea, you must first explain to the reader how balances of microbial life (bacteria, fungi, protozoa, nematodes, microarthropods, earthworms) are different in various stages of ecological succession. You must describe how the OVERALL HEALTH of any plant depends on how it has evolved to live in the soil conditions in which it is planted. You must describe how human activity effects soil food webs and how soil disturbed or treated with substances toxic to microbial life will move the soil backwards in succession. This will create a soil that favors weeds over crops by reverting the soil to bacterial dominance.”

Disproving any hypothesis (e.g. “compost tea prevents foliar disease) relies upon scientific evidence.  What Justin is asking for is not experimental but explanatory.  (There are several inaccuracies in what he outlines above, but in the interest of sticking to one topic I’m ignoring them.)

6.  “If you are going to debate compost tea you must disprove its ability to create a more fungal soil and inoculate the rhizoshpere with arbuscular mycorrhizae, improving soil born nitrogen. Excuse me, soil born proteins in the form of microbial biomass that are released as ammonium or nitrates in detritus, when consumed by predatory microbes, that are generally found to be lacking in human disturbed soils.”

The first point is incorrect, and is one of the hallmarks of pseudoscience – reversed burden of proof.  It is up to proponents of compost tea – or any other product or practice – to demonstrate efficacy.  (Wikipedia has an excellent overview of the characteristics of pseudoscience.)

7.  “You must prove: that most garden or Ag soils have a stable food web, the food web is not necessary, or that compost tea does not create a more complete food web. You must create a fair experiment (not paid for by cargill) that tests foliar applications on crops planted into a healthy rhizosphere with a complete food web.”

No.  Compost tea proponents must demonstrate that compost tea has an effect.  Period.  (It’s also important to understand that science doesn’t “prove” anything.  It either supports a hypothesis or disproves it.  That’s why scientific inquiry is a dynamic process – you never know when new evidence will lead to a paradigm shift.)

8.  “If you cannot present your findings in this way, you are misleading your readers knowingly. I was raised to classify that as a lie.”

I don’t conduct these compost tea experiments (though I do conduct research in other areas).  Part of my job as an extension educator is to read the scientific literature and translate it for use by nonscientists.  I have posted an extensive bibliography of the compost tea literature on my web site.  If I were either deliberately or accidentally misleading anyone, I would be in serious trouble with my university.  Given that I started my criticism of compost tea on my web site over 10 years ago, it’s likely that the information is not misleading.

Fan mail…NOT!

Below is an email I received this morning.  I’ve apparently made Justin really angry.  So as he’s requested, I’m giving him the chance to debate me.


Who owns you Dr. Linda Chalker-Scott?

You are a cheap mouthpiece and I don’t believe a word that you say. I’d debate you right under the table.
Any day, Lady.

Why don’t you just bring it on sister girl and first describe how vegetation thrived on this planet for millions of years before the phony baloney chemical crap that you use.

Even if your understanding of chemistry and physics is spot on about sprayed on nitrogen being identical to that in nature, it is unsustainable, it leaches, it costs more to the HORTICULTURIST than simple crop rotating methods. These chemicals disrupt the soil FOOD WEB; are you an ecologist? Are you a biologist?

All you are is a tart mouthpiece for the money monsters. This mail probably goes straight to the corporate lawyers that put those ugly lies in your mouth.
Compost can save the world; but you won’t let it, because it won’t pay for your next elective surgery."

So Justin, here’s your chance to air your complaint.  Let me know exactly what I’ve written that you disagree with and I’ll explain my position.  But keep it civil and keep personal comments out of it.

Permaculture – my final thoughts

We’ve had some good, vigorous discussion about permaculture, specifically around the book Gaia’s Garden.  I’ve pointed out some problems with the author’s understanding of relevant plant and soil sciences and will wrap up this week with a look at the glossary and bibliography.


The glossary contains a number of scientific-sounding words and phrases with unscientific definitions; for example:

“Buffer plants: Plants placed between guilds or between allelopathic species. They should be compatible with the trees in each guild and should have a positive effect on one or both of the guilds to be linked.” (“Buffer plants” is a phrase legitimately used in ecological restoration where plantings separate wetlands or other natural areas from human activity.)

“Guild: A harmoniously interwoven group of plants and animals, often centered around one major species, that benefits humans while creating habitat.” (The term “guild” is ecological and refers to groups of species that exploit the same types of resources.  It has been hijacked and redefined for permaculture.)

“Narcissistic: Plants that thrive on the leaf litter of members of their own family, such as the Solanaceae, or nightshade family.” (In this case, this is an unscientific term given a scientific-sounding – but nonsensical – definition.)

“Polycultures: Dynamic, self-organizing plant communities composed of several to many species.” (Polyculture is an agricultural term referring to the planting of multiple crops. It’s a cultural strategy in Integrated Pest Management.)

“Sectors: Areas where outside energies such as wind, sun, fire and so forth enter a site. These energies can be mitigated, captured, or otherwise influenced by placement of elements in the design.”


There are only two books I would consider scientific; one soils textbook from 1996 and the other is Odum’s classic text Fundamentals of Ecology (1971). I’m disappointed in how scarce and dated these references are, given the wealth of more recent articles and books that are both relevant to urban gardens and scientifically sound.

The bibliography also includes many books on design and I’m not including them in this critique. Of those that remain, the bulk are nonscientific and in many cases pseudoscientific. Examples of the latter include The Albrecht Papers (Albrecht, 1996), Weeds and What They Tell (Pfeiffer, 1981).

And this last criticism embodies what permeates much of Gaia’s Garden: pseudoscience. In the glossary, we see scientific-sounding terms or definitions that are ultimately meaningless or incorrect. Furthermore, we see scientifically legitimate terms such as guild used incorrectly. Both of these practices are characteristics of a pseudoscience.

I think this is unfortunate. I’ve mentioned before that I agree with much of the philosophy behind permaculture. But dressing up this philosophy as science both misleads nonexperts and alienates scientists.

So here’s a challenge – why not write a new book on permaculture and collaborate with a scientist? (I know a few who are writers!)

Building a Better Container

As most of you know, roots circling around a container isn’t considered a good thing.  And so people try various things to control circling roots.  One of the more creative horticultural minds out there, Carl Whitcomb, a guy why basically got sick of academia and went into private industry (and, as far as I can tell, loathes peer review and the whole process of publication), decided to see what he could do about making containers that don’t encourage circling roots.  He came up with a number of designs, but my favorite is the RootTrapper.  The container is made of a flexible cloth which roots get lodged in, preventing them from circling.  Not that I’ve never seen a circling root in a RootTrapper, it’s just that these circling roots are extremely rare.

A row of elms in RootTrappers

A cut open RootTrapper

This is one of those innovative products that really works and it surprises me that so few people use this growing system.  Yes, it’s a bit more expensive than standard containers, and yes, it does take a little more effort to take the tree out of this container than a smooth sided one.  But man, I’ve never seen a better root system come out of a container than those which you get out of these.

Permaculture – the discussion continues

We’ve started a robust discussion on the topic of permaculture, especially as applied to home gardens.  Let’s continue looking at some of the advice provided in Gaia’s Garden targeted towards home gardeners.

The book contains several lists of plants suggested for specific functions.  For brevity’s sake, I’ll just mention two:

“Host plants for Beneficial Insects” (pp. 157-159)
This list is prefaced in the text with “many of these florae are very attractive and can (and should!) be included even in the most formal garden bed.”  With this strong endorsement, the author then presents an unsourced list of plants, several of which are identified as noxious weeds in many states in the country.  They include Washington noxious weeds false indigo (Amorpha fruticosa), fennel (Foeniculum vulgare), Queen Anne’s lace (Daucus carota), toadflax (Linaria vulgaris), cinquefoil (Potentilla recta), sulfur groundsel (Senecio vulgare), and tansy (Tanacetum vulgare).

“Dynamic Nutrient Accumulators” (pp. 131-134)
We are told “certain species draw specific nutrients from deep in the soil and concentrate them in their leaves” and given an extensive table of these plants and exactly which nutrients they accumulate. The references for this table are not scientific, and in at least two cases are mystical in nature (Cocannouer’s Weeds: Guardians of the Soil and Pfeiffer’s Weeds and What They Tell).  As in the previous table, many of these plants are designated noxious weeds in Washington or other states and include nodding thistle (Carduus nutans), Canada thistle (Cirsium arvense), fennel (Foeniculum vulgare), toadflax (Linaria vulgaris), creeping thistle (Sonchus arvense), and tansy (Tanacetum vulgare).

As readers of this blog know by now, we GPs are not “plant purists.”  But it is highly irresponsible to encourage people to plant listed noxious weeds in their gardens.  Even the author seems to understand this, and states (on page 15) that “it is foolish to deliberately introduce a species known to be locally opportunistic.”  It’s mystifying, then, that he does exactly that in these two tables.

The inclusion of the table of “dynamic nutrient accumulators” demonstrates that this book tends to wander far afield of the philosophical roots of permaculture.  It is an excellent example of pseudoscience, as it creates a scientific-sounding phrase (“dynamic nutrient accumulator”) and misleads non-experts into believing a scientific claim (nutrient accumulation of specific minerals) without providing actual supporting data.

Everything is obvious once somebody shows you…

It’s amazing how many things in life seem complex when we try to figure them out for ourselves but then we end up smacking ourselves on the forehead when someone shows us how simple it really is.  The infield fly rule comes to mind.  Some colleagues of mine here at Michigan State may be on their way to such a solution for the problem of white grubs in lawns.  Drs. Dave Smitley (Entomology), Kurt Steinke, and Trey Rogers (Crop and Soil Science) are investigating the effect of mower height on turf damage from grubs.

European chafer grub.  Photo: David Smitley

The premise is simple: White grubs damage turf when they consume about 75% of the turf roots present.  Raising the mowing height of most standard mowers from 2” to the highest setting (usually 3 ½”) also results in more root growth; often by more than double.  Since there’s a limit to how much root mass grubs can consume, increasing the amount of roots ensures the damage threshold is never reached.  The working hypothesis has been confirmed by greenhouse tests and now the researchers are taking to the field.

Chafer grub damage.  Photo: David Smitley

This may turn out to be another example of how raising mower height and not trying to make your lawn look like a golf course fairway can reduce inputs and keep your turf healthier.