Corn Gluten Hub-bub-i-cide

Since the 1990's, corn gluten meal (CGM) has taken the gardening world by storm.  CGM is the protein by-product of milling corn, and this high-nitrogen compound was discovered by researchers at Iowa State University to be an effective pre-emergent herbicide, reducing seed germination by inhibiting root development.  Organic gardening and farming communities have quickly adopted this natural miracle substance as a method of weed control.

Continued research, however, is showing that CGM is, in fact, far from a natural cures-all for organic gardening.  It does not adversely affect existing weeds.  To the contrary, the nitrogen in CGM (about 10%) benefits existing weeds as much as the desired plants we're trying to help.  It's not a selective product, nor is it effective as a pre-emergent against all weeds.  Most importantly, it is failing to reach an important milestone to recommend its continued use; it seems unable to make the leap from greenhouse to the field.  While greenhouse trials demonstrated efficacy, field trials in the same locations have been unsuccessful.  Washington State University and Iowa State researchers found no differences in weed control on field-grown strawberries using CGM.  Researchers in California found that the use of mulch alone in containerized plants was more effective in controlling weeds than CGM.  California and Oregon researchers found no control of turf grass weeds by CGM, although the turf itself responded to the nitrogen in the CGM. The truth is that moisture, light, and warmth all affect seed germination and these factors are all much harder to control in natural environments than in the laboratory. Since CGM inhibits seed germination primarily by desiccating soil and denying moisture to seeds, it's no wonder that it does not work well in areas of the country with abundant moisture in the spring (most of America).  Linda Chalker-Scott, in The Informed Gardener Blooms Again, concludes that corn gluten meal may act adequately as a pre-emergent herbicide in the Midwestern US, but that it's not effective for western climates or for climates with abundant pre-spring moisture.

There are many lessons in the continuing saga of CGM. I've seen the step from laboratory efficacy to field efficacy fail often in pharmaceutical trials and surgical procedure trials in my chosen profession of veterinary medicine.  There are a couple of hidden messages here to gardeners as well, though:  First, organic gardening principles are great in theory, but it's obvious that weeding is so much of a chore that even organic gardeners will seize on any chance to reduce the work involved. So just who is kidding who?  Second, just because a substance is natural does not mean it's a miracle cure or that it is economical to use. We're going to be driving the price of corn high enough with all our driving around on the ethanol we derive from corn; we shouldn't throw our gardening budgets out of whack by using up even more corn as a partially-effective pre-emergent herbicide.  And if it is not useful as a herbicide, but we use it anyway as an organic fertilizer, somebody out there had better be doing some calculation on whether we use more inorganic fertilizer on Iowa and other Midwestern fields to grow the corn for a bag of CGM than the bag of CGM provides us back as organic fertilizer.  As the grandson of Indiana crop farmers, I guarantee you that no dirt farmer is growing 200 bushel/acre field corn without artificial nitrogen and herbicides.  Is CGM really "organic" or is it organized hype?

Crocus cavils

Yesterday, notwithstanding the six inches of snow we received 4 days earlier, the temperatures turned a balmy 76F and my giant "Dutch crocuses" (heavily hybridized Crocus vernus) suddenly bloomed.

Crocus 'Remembrance'

I wait every year for these crocuses to be those first prolific little flowers to brighten up my beds, but in truth, I confess that I'm not overly fond of them.  Now, before my readers tune me out entirely, I admit that my misgivings about Spring crocus are few and these little darlings do have their fine points, some of which are not widely known.  I know for instance, from Louise Beebe Wilder's writings, that Dutch crocus have a really nice scent if you lay down on the ground at their level, and having done so at risk of being observed and judged harshly by the neighbors, I can confirm Ms. Wilder's observations.  Gardeners in general seem to rarely pick these 6 inch beauties and raise them up to sniffing level as they would do with most other flowers, so those who haven't read Wilder do not seem to know this fact (I'll leave that alone now since this is not the time or place for garden literature snobbery).  Perhaps picking these diminutive blooms smacks too closely to plant abuse for many gardeners, but however you go about it, give them a sniff.  Children, as noted by the esteemed writer Henry Mitchell in The Essential Earthman, seem to be particularly prone to pick these giant colorful blooms and thus are often more familiar with the scent of these beauties.  The quickest road to hell, quoting Mr. Mitchell, is to "growl at a child for picking crocuses."  Henry seems to share my general ambivalence about crocuses though, calling them "vulgar" and recommending more stringent measures ("a tub of boiling oil") for children who pick irises or lilies without permission.



Crocus 'Pickwick'

 One of my minor complaints against Dutch crocus is that the Kansas winds tear the blooms to pieces quickly if they are not in a sheltered spot.  Many garden writers, such as Lauren Springer in The Undaunted Garden,  make a strong case for planting crocuses freely in warm season grass lawns such as the buffalograss that closely surrounds my house, but I've found that the crocus survive to please me only in my cultivated beds sheltered from the prevailing Spring winds of the Flint Hills.  Shortly after moving to this land, I planted over 100 Dutch crocus in the center patch of my circular driveway, but their blooms survived on this flat plateau only a day or two, if that, before the winds swept them away. The overall mass effect also dwindled over five or so years to nothing, despite my efforts to refrain from cutting the grass in this area until early summer.  I surmise that between the summer heat and the surrounding prairie grasses, they just didn't compete well in this area. When the flowers don't stay around, crocus are just not worth the planting efforts.

I'm sorry that I'm not a connoisseur, but I grow only the most common commercial varieties, the old deep purple 'Remembrance' and the striped 'Pickwick'.  I'm not fond of the common yellow crocus 'Yellow Mammoth', because this crocus is a little too orange or brassy for my tastes, like that of the daylily 'Stella de Oro', nor do I grow the white forms of Spring crocus.  As the result of choosing only the darker colors, my crocus don't compete well for attention against the gray remnants of last year's mulch unless you're looking for them, and that drawback is all entirely my fault.  I do look for them though, every year, to confirm that Spring continues to advance towards me and to ease me gently into the massive displays of daffodil and forsythia that come shortly afterwards.  Short-stemmed, short-lived flower or not, what would Spring be without a few gaudy crocuses in the garden?

Boxwood Issues

If you can handle the anger, frustration and disappointment of being a Kansas gardener long enough, you'll eventually receive the practical equivalent of a PhD in horticulture or plant pathology.  That wisdom, of course, comes in bits and pieces bestowed by innumerable little plants who came into your garden wholesome and happy from their nursery greenhouses and then exited from your well-intentioned care  in a brown and unhappy state.  Now, I'm not claiming that I am solely and personally responsible for all the plants that have expired in my garden despite or because of my efforts.  I'm certainly aided in that regard by ferocious winds, summer droughts, frigid winters, rabbits, deer, pack rats, and the occasional insect pest.  But when push comes to shove, I can usually point to a lack of knowledge or foresight that resulted in my abetting the actual criminals.

My hard-won garden lesson this year comes in the form of my front boxwood hedge, formed 8 years ago from twelve tiny plants of Buxus microphylla koreana 'Wintergreen'.  I planted this hedge around the curve of a driveway circle in front of the house to both define the circle when it was just a dirt and later a gravel path, and also to block a little Sha energy from the front entrance (some attention paid to Feng Shui never hurts).  These grew well for the first 6 years, but last year, in arguably the snowiest and coldest winter of the past decade, one bush in the center of the group had some stems which yellowed and died back. I wasn't sure of the cause, but a large snow drift did cover the center of this hedge for a couple of weeks in January, 2010, so I surmised it might be a little winter damage.  I treated it by some judicious pruning of individual branches and assumed new growth would cover the defect.

This year, after a second snowy winter, perhaps even colder than last, several of the center bushes have the same damage visible, as you can see from the pictures above right and below.  The picture below was taken just as the last remnant of another snow drift was melting, and as you can see, the damage is in the center of the hedge, right at the point where the highest drift occurred.  A little Internet research tells me that since it is unlikely that insect or fungal damage would occur only in the center bushes, this is probably just a classic case of winter injury to boxwoods.  Symptoms include yellowish, reddish, or colorless foliage, dead branches that occur particularly in the middle and apical parts of the crown, and loose bark or cracks in the stem, all of which fit my hedge.   Winter damage in boxwoods is exacerbated by allowing them to suffer in dry summers and  to go into winters without applying supplemental water, and I'm guilty of that since I haven't hand-watered these since 2005.  And it can be minimized by spraying with anti-desiccants in November and January, and my no-maintenance goals caused me to be guilty of that gardening transgression as well.  Guilty, guilty, guilty-as-charged.

Admittedly, hardy boxwoods are new to landscapes in the Flint Hills, and this hedge is an experiment to see if Global Warming has allowed us to shift climate zones.  After the severity of the past two winters, of course, I'm not sure that even Al Gore still believes in Global Warming.  I planted these because I like broadleaf evergreens more than conifers for Kansas landscaping, particularly since bagworms seem to be particularly plentiful in this area for gardeners who forego pesticides. I knew the constant cold dry wind in winter would be a challenge for the boxwoods, as would the full sun exposure of this area.  'Wintergreen' is one of the most cold-hardy of its cousins, as well as being the variety recommended to stay more green than bronze in winter so I thought I'd give it a shot. I also grow 'Winter Gem' and 'Green Mountain' in more protected areas as specimen plants and they seem to be doing alright where the wind isn't so dessicating and where the snow doesn't pile up.

So, for this hedge, instead of letting it grow au natural, unpruned, as I have in the past, this year I'm going to give it a second chance by pruning it to half-height, which will get rid of most of the damage and even out the topline.  I'll keep it watered better if it is a dry summer, but I refuse to stoop to spraying anti-desiccants.  the survival of these boxwoods is certainly dependent on thin ice, literally and figuratively.  Further bad winter damage in the near future and these babies get shovel-prunned in favor of something more resistant to the whims of Kansas.  Like a stone wall. 

Linseed Learnings

In a recent post I recommended the use of boiled linseed oil for the annual care of wooden tool handles and in doing so, and making sure I was conveying correct information, I got quite an education on linseed oil.  Here are ten facts about linseed oil that every gardener should know:

1. Linseed oil is actually flax seed oil.  I always wondered what a "lin" plant looked like.  Flax, I know. As an old man who hates burping  the fish oil recommended by the doctor, and who has been taking flax oil (also high in the Omega-3 fatty acids) instead, I think it's important to know that I'm preserving my arteries with the same crap that dries sticky and yellow on my wooden handles. Now the question is, should I, as a frugal gardener, save money and just drink from the $5.00 linseed oil can instead of buying the bottles of gel-caps?  Maybe the "do not take internally" text on the Linseed Oil can is a message in itself.

2.  The particular characteristic of linseed oil that makes it useful for our purposes is that it is a "drying oil" (along with tung, soybean, safflower, and poppy)  that polymerizes in combination with oxygen into a solid form.  It also shrinks very little on hardening and penetrates wood well. It is a traditional finish for gun stocks, cricket bats, billiard cues, and surfboards.

3.  In Europe cold-pressed linseed oil is eaten with potatoes and Quark cheese (a bland type of cheese).  The "hearty taste" of linseed oil supposedly offsets the bland taste of the cheese.  That means that a really terribly bland meal is made to taste like cardboard and is now considered edible.

4.  Linseed oil is water-repelling, but not water resistant.  Water penetrates a linseed oil finish in minutes and water vapour bypasses it completely.  Garden furniture treated with linseed oil may develop mildew.

5.  Linseed oil is a common carrier in paints, puttys and varnishes due to its drying properties.  Okay, no surprise, everybody knows this one already.

6.  Linseed oil was once used commonly to bind wood dust and cork particles into linoleum, a floor covering invented in 1860.  The use of real linoleum has declined as more durable PVC floor coverings have been developed.

7.  Linseed oil used to be boiled to cause it to begin polymerization and oxidation, thus making it thicker and shortening drying time.  Today most "boiled linseed oil" products are a combination of raw linseed oil, petroleum-based solvents, and metallic/catalyst dryers.  Modern boiled linseed oil is not edible, so stop chewing on the handles of your garden tools. 

8.  There was a National Linseed Oil Trust, formed in 1885 and based in St. Louis, that protected "linseed" interests in the United States.  It was dissolved in 1920 under charges that it violated the Sherman Antitrust Act.  As I read the history, essentially this was a linseed oil "cartel" that was accused of colluding to raise linseed oil prices.

9.  The polymerization of Linseed oil is an exothermic reaction, which creates a cascade of  heat buildup and make linseed oil-soaked rags particularly likely to cause spontaneous fires.  Always. always spread these rags out to dry before disposal and never just throw them into a trash can wet. 

10.  The primary world producers of flax seed  are Canada and China.  The United States was fourth in production in 2007 and almost all of the crop is from North and South Dakota, Minnesota, and Montana.

So, that's the short story of linseed oil.  Now that I know more about it, and have learned that it is one of the worst protectants of the natural oils against water, I probably need to choose something else to protect the handles of my garden tools.  Tung oil, for example, is more resistant to water, doesn't yellow with age, and would be a much better choice as a protectant.  But that brings up a whole bunch of other questions about using local versus imported substances (not many Tung nut trees are raised in the US) and the environmental effects of growing flax in mass quantities and on, and on.  Being a world-conscious consumer is so exhausting.