Knock It Off – Page 13 – The Garden Professors™

Building healthy soils?

I love living in Seattle…but I’m getting increasingly impatient with the City’s “Building Healthy Soils” propaganda. For years I’ve questioned their recommendation to perpetually amend landscape soil with organic material to no avail. Let’s see what you all think of their “fact sheet” (which you can read here in its entirety).

“The best way to improve the soil is to add plenty of compost or other organic matter throughout the entire planting area before planting. Thoroughly mixing these materials deep into the soil helps provide water, air and nutrients to plant roots.”

Hmm. No mention of how to determine IF your soil needs improving; without a soil test, you have no idea what your baseline organic matter level is.

But perhaps this recommendation is only for vegetable gardens and annual beds? Nope. In the next paragraph, we’re told to “Mix in organic material before planting lawns, perennials, trees and shrubs.” We’re given helpful how-to instructions: “Use a shovel or digging fork to mix amendments into the top 6 to 12 inches of soil. It is important to amend the entire planting bed — not just small holes for each plant. When planting individual trees and shrubs in lawns or existing beds, amend an area at least 3 feet wide, or 3 to 5 times as wide as root balls over 12 inches in diameter. Rototill large areas where digging is impractical.”

Now we’ve got a serious problem. This practice is recommended for existing beds. Not only will extensive digging or rototilling destroy any soil structure you might have, it will also take out the roots of any desirable plants in the vicinity).

But let’s continue to ignore reality and go on to the annual recommendations for adding compost to soils.
“Clay soils: 16 cu. feet (.6 cu. yard) = 2 inch layer of compost for new gardens. Use 1 inch per year in established gardens.”
“Sandy soils: 24 cu. feet (.9 cu. yard) = 3 inch layer of compost for new gardens. Use 1 – 2 inches per year in established gardens.”

Is the compost used as a mulch in these existing gardens? No – the guidelines are prefaced with this instruction: “Gardens: mix compost to 10- to 12-inch depth.” (Can’t say this does much for promoting root growth either.)

This document shows a breathtaking lack of understanding of how landscapes function, especially over the long term. It takes an agricultural practice (annual organic amendment of crop fields) and misapplies it to permanent landscapes. It is devoid of the research which continues to show that improper soil amendment can cause serious problems such as soil subsidence, perched water tables, and nutrient overloads. This last point is especially important to anyone living near aquatic ecosystems, since excess nutrients always end up in the water.

Before you plant this year, find out what your soil needs before amending it. And remember that mulching is the natural (and sustainable) way to add organic matter to the soil.

Another fine product…

I’m spending this week in Palm Desert, CA for a little R&R in the sun. In the morning, with my pot o’ Earl Grey, I read the local paper (The Desert Sun). Last Sunday’s paper provided me with an article about an “intelligent water incubator” (all material in quotes was taken from the article). Pieter Hoff, a “Dutch scientist, author, and major exporter of lilies and flower bulbs” has invented the Waterboxx, which “produces and captures water from the air through condensation and rain.” He claims a four year test in the Moroccan Saharan desert showed an 88% survival rate for fruit tree saplings “grown without irrigation.” He now wants to test his invention in the Coachella Valley desert “to create a money-making business model with trees” and of course to help save the environment.

The Waterboxx is a plastic rectangular box, but we’re told the inner technology is more complex. The box is put around the seed or sapling and provides water “in small doses.” It also “protects roots against sun, wind, weeds, rodents and some animals.”

I visited the web page and you should too. The technology section is fascinating. It includes an animation explaining how the box functions; apparently the box was designed to protect seeds in the same manner as bird poop. I was interested to see that the box requires 4 gallons of water when it’s set up; not exactly a “no irrigation” methodology. And that a wick inside the box releases about 50 ml of water a day to the soil below the box. The last frame tells us “with the waterboxx we can transform most of the deserts into forests.”

I won’t test your patience by dissecting all the silliness in this article and the web site. As you might expect, there is no peer-reviewed science on this product, nor even a research report. The plant and soil science is marginal; the ecological science is horrific. The box effectively prevents water from reaching the soil around the seedling, doling it out in miniscule doses instead. Not only could a decent organic mulch layer do the same job (and do it better), but I question the “greenness” of creating yet another plastic product with a limited lifespan. This system is so removed from reality that it’s incredible that anyone takes it seriously – yet it’s been out there for several years now and has won several awards.

Oddly, there’s little specific information about the inventor. All I could find definitively is that he comes from a bulb-raising family in The Netherlands and has written a book: CO₂ – a gift from heaven (under the name Petrus Hoff).

Protecting existing trees – what a concept!

I just got back from a trip to Pullman where I guest lecture once a year for the Landscape Plant Management class. It’s also a chance to get some new photos for my Wall-O-Shame. Here’s my latest:

Pin oak (Quercus palustris) doesn’t drop its leaves in the winter – instead, they hang on until the following spring. So it’s really easy to see which part of this tree is alive (i.e., has last year’s leaves). It’s apparent that most of the crown has died, with only some lower scaffold branches remaining.

How did this happen? Take a look at how new that concrete is around the base of the tree (and how small the tree well is. This construction was done in 2004:

Note the complete lack of root zone protection. Not only has the majority of the tree’s fine roots been destroyed in preparation for pouring concrete, but only a very small space under the tree is “protected.” I guess the cup at the base represents the irrigation system. To top it off, this construction was done in August, when coincidentally I was there as well. It was blistering (as it usually is in the summer in eastern Washington), and the remaining leaves on this tree were wilted:

So why would anyone be surprised when, 6 years later, this tree looks like crap? And why doesn’t WSU insist on tree protection standards when construction bids are submitted?

A Public Service Announcement (of sorts)

File this under “short-sighted acts of government”. What, that cabinet is full to overflowing?

In the wild world of U.S. Land Grant Universities, faculty appointments can consist of varying ratios of “the three missions”: Teaching, Research, and Outreach. The Cooperative Extension Service is the formalized version of outreach. Three of us Garden Professors (Linda, Jeff, and Bert) have Extension appointments. I personally do so much outreach with both gardeners and industry that everyone thinks I’m in Extension, so I’ll consider it an honorary appointment.

Extension does so many fabulous things for so many people, space does not allow me to even get started. It’s not “plows and cows” anymore – urban areas receive amazing benefits in terms of environmental education, programs for K-12 (e.g. 4-H), family and consumer services, and big push over the last decade in urban horticulture.

Among all the programs Extension administers (and there are loads), the program I’m most partial to is Master Gardeners (MGs for short). I instruct training sessions, and give gardening talks across the state. Once trained, MGs provide gazillion volunteer hours at no charge to the state, in areas as diverse as consumer horticulture to school gardening. Our campus garden utilizes volunteer hours from MGs on nearly a weekly basis

Hang in there, I’m getting to the point.

Cooperative Extension has been prone to budget cuts for quite a while now – for most states, the fat was long ago cut away, and further cuts are going straight to the bone. Imagine the alarm when out of the blue yesterday came an email update on the state’s legislative issues and actions, most of which are actions on our huge budget shortfall:

Virginia Cooperative Extension (VCE) & Agriculture Research Stations
Introduced Budget: Reduction of $1.1 million in FY1; reduction of $4.5 million in FY2
House Budget: Mandates a restructuring of VCE: Closes offices in Alexandria, Arlington, Fairfax, Norfolk, Petersburg, Portsmouth, Prince William, City of Richmond; Consolidates [an additional] 13 offices [moving to a nearby county]; Eliminates Family & Consumer Services, Community Vitality, and lawn/garden programs statewide leaving an emphasis on agriculture programs outside the urban corridor. Savings of $2.5 million in FY2. Senate Budget: No change from introduced budget.

This proposed budget would effectively close down Extension in (by far) the most heavily populated areas of Virginia – Northern Virginia, the Richmond area, and the Virginia Beach area.

From Dave Close, our Virginia MG Director, comes these figures:

“Statewide in 2009, our more than 5,000 VCE MG volunteers reported in excess of 334,000 volunteer hours (at a value of $6.76 million) and more than 577,000 contacts. We have right at 60 individual MG units that provide coverage of 85% or so of our counties and cities statewide.”

Dave goes on to note more good things that MGs are involved in:

1) Environmental quality (air, water, and soil; rural-urban interface concerns such as wildland fire and how it can impact personal property and what to do to mitigate against the potential threat of wildland fire, etc.)

2) Working with youth (school and community gardening programs for instance)

3) Value of the landscape (economic returns from sustainably maintained landscapes – tax revenue from personal property, ecotourism, local economic development, personal savings realized from strategically planted trees in your landscape to reduce energy bills, etc.)

4) Food safety and security (growing your own food, local food initiatives, farmer’s markets, knowing how to safely store and preserve the food you grow, biosecurity and dealing with invasive plants and pathogens, etc.)

5) Quality of life improvement (working with populations with limited skills or abilities, working in detention centers for youth or adults giving them usable trade skills in the green industry, public health and safety issues such as mitigating against public health concerns such as west nile virus, etc.)

Now take a look at that House budget again – eliminating VCE in the most populated counties results in a one-time savings of $2.5 million. 2009 Statewide value of MG hours: $6.76 million.

I know many, many other sectors of public service and higher education are also in critical condition. But cash strapped state or not, I’d call this cutting your nose off to spite your face.

Water droplets and burned leaves, continued

A few weeks ago (January 20 – “Help, help, the sky is falling”) I started a discussion about an article appearing in the peer-reviewed journal New Phytologist. That posting focused on the methodology and results in the paper. Today let’s take a look at the authors’ underlying arguments (their introduction to the study) and their conclusions.

1) The authors’ premise is that “laymen and professionals alike commonly believe water drops on plants after rain or watering can cause leaf burn in sunshine.” To support this statement, the authors surveyed “relevant topical websites.” They found 29 sites (primarily .org and .com, but no .edu sites) that agreed with this statement and 9 sites (including 4 .edu sites) that disagreed. How this translates to “professionals” believing that water drops cause sunburned leaves is unclear, especially when all the .edu sites surveyed disagreed. In my opinion, the authors should have surveyed ONLY .edu sites to test their hypothesis about what professionals believe. And why only 38 sites? We’re not told how or why these sites were selected.

2) Building on this shaky premise, the authors then address the apparently popular concern that water drops can cause forest fires. They survey “the forestry literature” to find “the prevailing opinion is that forest fires can be sparked by intense sunlight focused by water drops on dried-out vegetation (Table S3).” Table S3 is not included in the online article but is in a supplementary file. Happily, it is short enough that I can paste it in here (so you can find the sites yourself):

Table S3 Survey of websites discussing the possibility of forest fires due to sunlight focused by water drops. We posed the question: “Can sunlit water drops spark forest fires?” The rate of the ’yes’ answer was 3 / 3 = 100%.

URL	Title of article	Answer
URL	Title of article	yes	no
http://fotozz.hu/fotot_megmutat?Foto_ID=30936	Forest fire and water drops	+
http://mek.oszk.hu/01200/01214/01214.pdf	Radó (2001) Role of vegetation in protection of the environment	+
http://wiki.answers.com/Q/Whether_presence_of_water_cause_forest_fire	Whether presence of water cause forest fire?	+

I must say this took my breath away. This is not a survey of the “forestry literature.” It is 3 websites, two in Hungarian and one in English, chosen for unknown reasons. The first site is actually a stock photo website with comments about pictures of water drops on leaves. The second is entirely in Hungarian and is not in the scientific databases. The third is in English, and here’s what “wiki answers” has to say:

“When I was a youngster and could not afford a magnifying glass, I would twist a piece of wire around a pencil so that it formed a round piece at the end of the wire. I would then dip the rounded end into water so that a blob of water made a very small magnifying glass. I suspect that when it has rained this same effect is left on leaves, millions of tiny magnifying glasses all concentrating the suns rays onto what they happen to land on. Just one tiny focal point of a rain drop could possibly generate enough heat to start a fire. Robert”

[Note to the editors at New Phytologist: What I really want to know is how this kind of junk science can slip through peer review. It is embarrassing.]

3) The authors (none of them plant scientists) nevertheless address plant ecophysiology in the discussion: “If, after rain, leaf blades were covered by a water film, they could not breathe, because gas exchange through the stomata would be blocked…To avoid this, plants evolved efficient water-repelling and water-channeling structures which build up and roll off rain drops. For example, water drops easily roll off the highly hydrophobic leaves of lotus, Ginkgo (Fig. 2b), and floating fern (Fig. 3b,c) if leaves are tilted or shaken.”

Two comments here: the stomata through which terrestrial plants “breathe” are primarily on the underside of the leaves. It is true that floating aquatic plants have most of the stomata on the upper leaf surface. Which leads me to ask…if water drops easily roll off of floating fern leaves, then how did the researchers do the following? “…the experiment was concluded by cutting and scanning several Salvinia leaves – still holding water drops – in the laboratory in order to document their sunburn.”

4) The conclusion of a research article, as any Garden Professor knows, is meant to summarize the results of the experiment. Yet the last paragraph of the conclusion reads as follows: “Lastly, a similar phenomenon might occur when water droplets accumulate on dry vegetation (e.g. straw, hay, fallen leaves, parched grass, brush-wood) after rain. If the focal region of drops falls exactly on the dry plant surface, the intensely focused sunlight could theoretically spark a fire. However, the likelihood of this is considerably reduced by the fact that after rain the originally dry vegetation becomes wet, and as it dries water drops also evaporate. Thus, claims of fires induced by sunlit water drops on vegetation should also be treated with a grain of salt.”

Even though the authors seem to discount the possibility of these scenarios, they did NOT test the ability of water drops to cause combustion. This speculation really belongs in the discussion, if anywhere at all. So why is does it make up 50% of the conclusion? The cynic in me says it’s because 90% of the people looking at this article will read only the abstract and the conclusion – and this is especially true of nonscientists. It’s a great way to get immediate attention, even with a complete lack of supporting evidence.

Don’t believe me? Just type in “water drops cause forest fires” without the quotes into Google. 146,000 hits, and all the top ones reference this article.

“Being wrong” counterpoint

I haven’t finished with the water droplets story yet – but I just had to add some more evidence to the tree planting discussion from last week.

Consider this series of photos below. This is a street tree in Kennewick, WA (in the southeastern part of the state, where summers can be intensely hot and dry). Every spring, this tree leafs out just fine – and every summer the leaves suffer marginal and tip scorch. This is a classic symptom of chronic drought:

As an amenity, the tree fails. Even though the landscape is well-watered, as shown by the healthy turf in the next photo, the canopy is sparse and dry.

An excavation of the roots explains why: the tree was planted too deeply and has developed a secondary set of roots:

Note how sparse these roots are – which is typical of many adventitious root systems. While the roots are adequate for water uptake during the cool spring weather, the hot dry summers suck away more water from the leaves than this puny root system can absorb, even when well-watered.

My point: sure, trees might survive being planted too deeply. But thrive? Not in this case – and this is a well-managed landscape! With less care this tree would have died long ago. The only solution here would be to replace this tree – correctly.

Why I dislike rootgrafted plants

I’m pretty much a live-and-let-live person in terms of plant choices (as long as they’re not invasive). But I’m becoming convinced that oddities grafted onto hardy rootstocks are poor choices, because the rootstock always seems to win. I posted one of these several months ago (see October 28, 2009 ), but just today have just found the poster tree for my anti-rootgraft movement.

A little backstory. I’m currently out at the Washington coast, trying to get some writing and seminars done without disruption. Today I had to make a trip into Aberdeen, the horrors of which will have to wait for another post. Before going back to my retreat, I tried to renew my enthusiasm for life by seeking out bad plants. I was well rewarded.

I have to give my daughter Charlotte credit for spotting these lovelies. There were two of these $50 Betula pendula ‘Youngii’ trees available. I felt like I’d stumbled upon the next winner of “America’s Next Top Model.” I took pictures from every angle, full shots and close-ups, for your viewing enjoyment.

Note that the “unusual deciduous tree with pendulous branches” is a grafted tree, evidenced by the differences in girth at the grafting point. You’ll also note the appearance of vigorous watersprouts emerging from below the graft. (The bamboo stake to the left lost it function years ago, but is still adds an unexpected pop to the overall composition.)

And here she is in her full beauty! The “S” curve of the scion is bisected longitudinally by two watersprouts, forming a giant $! I do have to agree with the tag at this point – it certainly is “an excellent accent or specimen plant” for the Island of Misfit Grafts.

Finally, please enjoy yet a final reason I don’t like grafts:

(Hint: Note the glue glob.)

Post-holiday Poinsettia Fatigue

You’ve seen them. The saddest thing ever – a poinsettia, still in its little foil sleeve, tucked into the corner of the doctor’s office/bank/etc. In June.
Photo courtesy of Beth Bonini http://beedrunken.blogspot.com
So iconic, there’s even a rock band in St. Paul called “Dead Poinsettia.”

Every year about this time, I get asked “how do I care for my poinsettia so it will bloom next year?” by friends, students, random callers, and random newspaper writers.

Two words: Chuck it.

Four reasons:
1) Unless you have a greenhouse, you probably can’t replicate the growing conditions that resulted in that lovely, leafy, perfect plant. That poinsettia has been grown under optimal temperature, humidity, fertilizer, and high light conditions. It’s also been sprayed with plant growth regulators – often multiple times, to keep the internodes from elongating. Even with all the breeding for a compact habit, they still want to streeeeetch to be the shrubs/small trees their forefathers were back in Mexico.

2) Day length. Poinsettias are obligate short-day plants, which means they require a long dark period (yes, I know, why don’t they call them obligate long night plants) to become reproductive, resulting in red (or pink or cream) bracts and the little yellow flower-thingy in the center (the cyathia). You can, of course, stick it in a dark room at 5:00 p.m. and remove it to a lighted area at 8:00 a.m., every day for the months of October and November. Until you forget over that long weekend and leave it in the dark for three days…

3) Help stimulate the local “grower” economy. Consumerist, I know, but wholesale and retail greenhouses grow poinsettias to keep their full–time employees working during what is otherwise a very dead time in the ol’ floriculture business. Seldom do these businesses make much of a profit on poinsettia; the plan is to keep everyone busy and generate a little cash flow. Now, some growers/garden centers go above and beyond the usual 6” red point, with unusual cultivars in a range of colors and sizes, hanging baskets, poinsettia “trees”, etc. This has proven to be a great strategy for some enterprising growers.

4) Poinsettia = total whitefly magnet.

In light of the above, I recommend enjoying your poinsettia until the leaves start dropping…then once it reaches the “less than fresh” stage, add it to the compost pile. Next season, go to your local independent greenhouse or garden center and buy a new one. Finally, if you are one of the hard-core, stick-with-it types that has been successfully reblooming the same poinsettia for three years running, congratulations! You have much, much more patience than I do.

Disclaimer: My Master’s research was on poinsettia and the effects of nitrate- N:ammonium- N ratio on growth thereof. Five treatments x 6 replications x 3 cultivars = 90 poinsettias, off of which I picked every leaf and bract to run through a leaf area meter. The latex oozing from the petioles made for a gloppy mess and the whole process took five days. Even 15 years later, I can barely look at a poinsettia without cringing. Pleh.

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Sunday rant – the evils of chemicals

It’s days like this that I am so grateful to have this blog at my disposal!

It’s 7 am on Sunday and I’m just finishing the paper, drinking Earl Grey tea, and listening to NPR. Liane Hansen just finished an interview with Martha Stewart, who among other things was discussing healthy eating for the new year. She’s a proponent of organic food (as are many of us), and mentioned two reasons she doesn’t like conventionally grown produce. The first – residual pesticides – is a legitimate concern. But then she stated her second concern that “chemical fertilizers in the soil are taken up and stored in the plant.”

No kidding.

Plants really don’t care (excuse my anthropomorphizing) where their mineral nutrients come from. Nitrogen in ammonium sulfate is the same element as the nitrogen in cottonseed meal. The plant uses it for amino acids, chlorophyll, alkaloids, and many, many other compounds.

Martha’s faulty thinking falls into the “organic is safer than chemical” mindset that way too many people hold (you can read a column I wrote about this in 2001 here). “Chemical” is not intrinsically bad and “organic” is not automatically safe. This is an emotion-based argument and inspires fear rather than thoughtful discussion. When someone parrots this mantra, I can’t take them seriously.

I believe that organic methods in production agriculture, ornamental landscapes, and home gardens are superior to conventional practices and support a healthy soil-microbe-plant-animal system. I also believe that many fertilizers are misused and/or overused – but this includes both conventional and organic varieties.

Gerald Holton, a science historian at Harvard, once stated that “persons living in this modern world who do not know the basic facts that determine their very existence, functioning, and surroundings, are living in a dream world. Such persons are, in a very real sense, not sane.”

This is the quotation that came to mind this morning.

Will cocoa mulch kill my dog?

Recently I was asked to comment about a rash of e-mails floating around cyber-space concerning the toxicity to dogs of mulch made from crushed cocoa bean hulls. Cocoa mulch is by-product of cocoa production. The dark brown mulch is aesthetically and aromatically pleasing, giving the garden a rich, chocolately scent. Since theobromine, a naturally occurring compound in chocolate is toxic to dogs, the internet is now filled with cyber-legends of dogs eating cocoa mulch and keeling over dead.

According to an article published in the Journal of the American Veterinary Medical Association (JAVM June 1, 2006 p. 1644), cocoa bean husks can contain up to 2.98% theobromine. The JAVN article state “no reports of lethal toxicosis from ingesting this mulch have been filed with the ASPCA Poison Control Center this year (2006). In 2004 and 2005, 16 reports of single exposure to the mulch were received, none resulting in death.”

The ASPCA posts this comment regarding cocoa mulch on its website:
“Dogs consuming enough cocoa bean shell mulch could potentially develop signs similar to that of chocolate poisoning, including vomiting and diarrhea. In cases where very large amounts of mulch have been consumed, muscle tremors and other more serious neurological signs could occur. To date, the ASPCA Animal Poison Control Center has not received any cases involving animal deaths due to cocoa mulch ingestion. One key point to remember is that some dogs, particularly those with indiscriminate eating habits, can be attracted to any organic matter. Therefore, if you have a dog with such eating habits, it is important you do not leave him unsupervised or allow him into areas where such materials are being used.”

It should be noted that processed cocoa mulch may contain much lower concentrations and some manufacturers market cocoa mulch that is ‘Pet safe’. Consumers should look for products that are tested and certified theobromine free.

As always, I stand by my recommendation to use locally processed wood products such as ground hardwood bark and ground pine bark. Plants grow well in these mulches, which are typically among the most cost-effective and natural looking (to me, at least) mulches available, and they are renewable and help support your local economy.