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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.

Glossary

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.”

Bibliography

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.

Some Super-Cool Stuff

For the past ten years or so I’ve worked to try to transfer information about horticulture to people. It sounds simple, but it actually took a lot of time and effort to figure out the best way to do it, and I’m still not there yet — and probably never will be. The reason that I mention this is because I appreciate it when another horticulturist, such as my fellow garden professors, work to get information about horticulture out to the public. So yesterday we had a speaker come to our depoartment to give our annual end of the year lecture — It’s kind of a big deal for us — We usually have a big name person (horticulturally speaking of course) and pay him or her pretty well and have a reception. It’s nice. We also hand out scholarships to our undergraduates who earned them and any awards which we have to give. But anyway, back to the speaker. This year we had a guy come in who I’d never heard of before besides some strong recommendations from some of my colleagues here in the department. I also did a cursory check of his website. I liked what I saw, but I wasn’t blown away. Sometimes I’m such a dingbat. Simply put, this guy gave one of the top two or three horticultural (actually I should say botanical — it’s more botany than horticulture) presentations which I have seen. His name is Roger Hangarter and he is a professor at Indiana University. In a nutshell he films plant’s moving using time-lapse photography to demonstrate important concepts. Here is one of his websites:

http://plantsinmotion.bio.indiana.edu/plantmotion/starthere.html

But if you do a google search for him he has a lot of other things on different sites. He has even created a traveling display for museums called slowlife. Very, very cool. There aren’t a lot of people who I’m in awe of — but this guy is one of them. If you have a garden club or run a master gardener program you NEED to get this guy on your calendar if you can.

Permaculture – beginning a discussion

Among other things, part of my job involves reviewing educational materials for use in WSU’s Extension programs related to urban horticulture. One of the books is “Gaia’s Garden: a guide to home-scale permaculture” (T. Hemenway). It occurred to me that my review might also be of interest to our GP readers.

I’ve created a fairly extensive review and I will break it into separate posts over the next few weeks. So let’s start the discussion off with a topic we already know is inflammatory: invasive species. To be clear, we are not talking about the many introduced species, plants and animals alike, who appear to be well-behaved in our country. Here’s my take on “The Natives versus Exotics Debate” (pp. 12-17):

The author, with no formal training in biology past his bachelor’s degree, states that “calling a species ‘invasive’ is not good science.” This will come as news to researchers in the field of invasion biology. He blithely disregards the real environmental and economic damage caused by invasive species and erroneously believes that invasive species selectively appear only as a result of human-caused environmental disturbance. Apparently natural disturbances (from fire, volcanic eruption, flooding, etc.) don’t open themselves up for invasion (again, a notion that is incorrect and refuted by a number of obvious examples, such as the 1988 zebra mussel invasion of Lake St. Clair and the subsequent colonization of many freshwater habitats). The author seems not to understand that there may be unfilled niches in certain ecosystems that can be exploited by invasives, endangering native species whose niches may overlap; there are obvious lessons from Hawaii, Australia, and other parts of the world. In any case, the author’s naive tolerance of invasive species is a poor example to follow and certainly not based on current, mainstream science.

So, fans of permaculture, what do you think? If permaculture is a legitimate science-based practice, how do we reconcile the very real issue of invasive species? If you disagree with me, keep in mind one of the hallmarks of pseudoscience: attacking the motives or character of anyone who questions the claims. The arguments should contain content, not insults.

Call for “visiting professors”

I’ll be posting my usual blog later today…but in the meantime we’ve got an invitation for you.

Are you, or someone else you know, a "Garden Professor?" In other words, do you use current, relevant plant and soil sciences to inform yourself and others? If so, we invite you to submit a guest posting to our blog.

We’ll post your article without editing, though we may make comments.

If you’d like, send a photograph of yourself and any other illustrations you want posted along with your blog.

We can’t offer any compensation other than the glory of being an online Garden Professor – but isn’t that enough? We think so!

If you or someone else you know is interested, please contact one of us directly. My email is lindacs@wsu.edu.

Killing with Kindness

With the advent of Spring comes a myriad of calls on distressed plants from homeowners, nurseries and landscapers. One of our better tree service companies (I’ll call the owner/operator ‘Mark’ to protect his clients’ identities) in southeastern Michigan called with a series of problems this spring so I decided to take drive over and get a first hand look. We looked at several problems on plants ranging from trees to ground covers but there soon emerged an consistent thread: overwatering. Plant problems related to overwatering and poor soil drainage are among the most common landscape issues I see year in and year out. The stops I made with Mark last week were typical. Mark works in several very affluent suburbs around Detroit (I know readers around the country don’t associate Detroit and affluence, given our recent press, but there is still some serious money in the area). Some of Mark’s clients spend up to $20,000 per year just to maintain the trees and shrubs on their property – that’s not including lawn maintenance. Needless to say, these folks want everything perfect. In their effort to have their landscape look more perfect than the neighbors, the homeowners and their gardeners often go overboard – especially with irrigation. One of the things that caught my attention during our site inspection was recurring issues with Norway spruce. For the most part, we regard Norways as a cast iron plant and one of the last trees with which we’d expect to have problems. Yet we saw several instances were established specimens were suffering needle die-back and declining.

In each case the trees were irrigated in situations where they would likely grow well without supplemental watering. But the trees were surrounded by ground covers or annual beds with heavy soils that were heavily irrigated. Problems usually increased on down-slope positions.

The solution? Back off the irrigation. Everyone knows trees need water, but roots their roots also need oxygen. At one site we visited, the homeowner already had his gardener running the irrigation system – in April! This is truly killing with kindness. Most established landscape trees, shrubs and perennials in this part of the world need little, if any, irrigation. Newly planted trees and shrubs need an occasional (weekly to bi-weekly) drink in the first year and some follow-up the second year. After that they can manage most years on our rainfall. In the end, a lot comes down to design. Establish thirsty annual beds where they can be irrigated without drowning hardier trees and shrubs.

Selling dawn redwood

As with last week, this past week and weekend were largely occupied by my role as a faculty advisor for the MSU Horticulture club. This weekend was our annual Spring Show and Plant Sale. Each year our undergraduates commandeer the Horticulture department’s conservatory, bring in a boatload of plants, pavers, turf and mulch and design and install a landscape. It’s actually quite a process to watch. http://www.youtube.com/watch?v=4NTPzB6YVSk
In addition to the Spring Show the Hort Club puts on a plant sale, which is the group’s principle fund-raiser for the year. My duty station for this year’s plant sale was working outside in the tree sales yard. For the record, retail is not my thing but, hey, it’s for a good cause. The star of our tree sale this year was a container-grown 14’ dawn redwood (Metasequoia glyptostraboides).

For those not familiar with this tree, dawn redwood is an incredible tree. It’s a deciduous conifer, similar in many respects to bald cypress (Taxodium distichum) but with a finer, more refined character. Metasequoia is considered by some to be a ‘Living fossil’, similar to Gingko biloba. The genus Metasequoia was originally described in 1941 from Chinese fossils from the Mesozoic era. Although local people in China knew the tree and used it as an ornamental, living trees were not formally described by botanists until 1948.

Dawn redwood is well adapted to wetter sites

Seed collected by Arnold Arboretum in the late 1940’s were distributed to universities and arboreta and this attractive, fast-growing tree found its way into the nursery trade. Ironically, millions of Metasequioa have been planted as ornamental trees but the species is considered critically endangered due to loss of its native habitat in China. Dawn redwood is extremely fast growing and some trees planted in the U.S. from the original collections in the 1940’s are reportedly 3’ in diameter.

Dawn redwoods on MSU campus

So, how did I fare in nursery sales for a day? Put it this way, I better hang on to my day job; retail is still not quite my thing – though I did move the dawn redwood and got to spend a good bit of my weekend talking about this awesome tree.

Dandelions and clover

It was fun to read all of your comments last week about your opinions on lawn care. To follow up on it I’m going to talk a little bit about why I’m not fond of companies which apply herbicides multiple times throughout the year. But first I think I’ll mention why I apply herbicides at all — aesthetics. That’s it — the whole reason. Could I go the no-lawn route? Yes, but I like having a yard to run in. Not a huge yard, but a little yard to play tag with the kids.

What I long for though is the yard from the house that I grew up in. Our house in southeastern PA (About an hour west of Philly and an hour east of Lancaster) was set back about 800 feet from the road and was on old agricultural land. The area around the house was planted in grass in the mid 70s and then it was left alone. Fertilized once the first year I think, but that’s it. Dandelions invaded quickly as did clover. Over the years the clover began to dominate the grass, but not to the point that the grass disappeared, and the lawn actually appeared relatively homogeneous. Dandelions never left, but their numbers declined. The clover grew low and the grass never shot up like it does in a heavily fertilized lawn and so mowings only happened once every two weeks or so (well, OK, sometimes more often depending on the weather and where on the lawn you were — the spot over the septic tank needed mowing every 48 hours or so). The grass did go dormant most summers, but 800 feet from the road there wasn’t anyone to complain, and besides, the clover kept the lawn from appearing completely scorched. The lawn looked good for well over 30 years (until my parents remodeled the house and the yard was torn up).

The typical suburbanite might not have liked this lawn, but to me this lawn looked great, and, besides, it was low maintenance. The reason I’m bothering to tell you about this lawn though is because it illustrates so well what lawn care companies make impossible. They say (and by “they” I mean professors like myself) that pesticides beget pesticides and fertilizers beget fertilizers, and nowhere is that as true as in a well manicured lawn. The herbicide of choice is 2,4 D (though there are many others that are used) which lawn care companies apply multiple times over the the course of a year. This pesticide does a great job of killing dandelions, but it also kills clover. It rarely hurts grass unless it’s grossly over-applied. The problem with killing clover is that this clover is the stuff that fed the grass in the house where I grew up. Clover takes nitrogen out of the air and makes it available to grass every time the lawn is mowed (the clipped off pieces of clover degrade and the nitrogen in them feeds whatever plants are around). Without the clover you need to add fertilizers. So, because the lawn care company is keeping the lawn free of weeds they also need to fertilize because they’re killing all of the natural fertilizer. Here’s the thing, the weed that most people in the suburbs like least, dandelions, is actually very sensitive to low potassium. The lower the potassium in the soil the worse it does. In fact, dandelions can easily be out-competed by grass and clover if potassium is low — just as happened in the yard of the house where I grew up. But do lawn care companies pay attention to this (by using high nitrogen, low potassium fertilizers?) What do you think?

My guess is that many of you thought that I’d cite all kinds of scary side effects of the pesticides used on lawns. Nope. In general I think that, if used properly, they’re pretty safe for humans (with a few notable exceptions). I’ve spent a lot of time reviewing epidemiological and toxicology studies and I can think of many worse things. I am somewhat fearful of what 2,4 D may do to dogs in particular — they can’t excrete this poison like we can. Don’t think for a minute that I’m calling these poisons perfectly safe — I just think there are plenty of other better established reasons to avoid lawn care company pesticide schedules.