Publications (Paul's Blog)

March 26, 2010

WEEDS 101

Filed under: Uncategorized — Paul Dowlearn @ 11:47 am

With all the rain we’ve had this year we have some really healthy weeds. Our local county guys mowed the road ditch in June like they normally do, only this year they had to go back and do it again in July since it kept raining. The Johnson grass was over 6 feet tall again just two weeks after the first mow. Yessir the situation was indeed scary.

Being the crafty (and basically lazy) person that I am, I decided to take this year to experiment a  little. Over the years I have learned and listened to various theories concerning every gardener’s nemesis,  our unending battle with weeds. So I decided to let most of the weeds in the vegetable garden grow since it was obvious that they were going to grow faster than I could pull’em.

One of the things I have learned is that fast growing annual weeds are great soil improvers. The deep carrot-like roots reach far into the soil to bring minerals up to the leaves. At the same time these roots are penetrating sub soils to loosen them up for other plants to colonize later. Meanwhile the minerals and elements are deposited on the surface as the weeds decompose each winter. Eventually this forms a rich enough soil for a higher order of plants with their accompanying soil microbes. This makes perfect sense to me so when I look upon my vegetable garden this year I don’t feel threatened by the 10 foot tall weeds. I’m seeing 10 foot of biomass that will result in improved soil for next year. At least that’s what I’m counting on.

Noted author and landscape visionary Sally Wasowski calls weeds “Mother Nature’s band aids.” I agree with this concept wholeheartedly. Once it is understood that the role of weeds is to improve soils and prevent erosion then a tall stand of weeds is not so imposing. However, this natural cycle from disturbed soil back to climax grassland or woodlands may take several decades to evolve. What we as gardeners would prefer is to do this in one quick easy step. That is much easier said than done. The following are a few of my own weed experiences that I hope will help you.

1. Tall guys shade out the short guys. Ever wonder why many of the hard to eradicate weeds like Johnson grass are so persistent? Tall weeds grow quickly to steal available sunlight thus making it very hard for shorter plants (like your lawn grass for instance) to gain a foothold. The simple act of regular mowing will easily disrupt tall weeds and give the short guys a chance. As you continue to mow, tall weeds will not be able to flower or set seed. Eventually the roots themselves will begin to starve as the plant cannot produce enough chlorophyll because it is being denied it’s normal height. Yes, I have wiped out stands of Johnson grass with nothing more than a lawnmower and patience.

2. Weeds prefer disturbed soils. Just try tilling up a garden patch or a new spot for ornamentals and you will get the message. Many successful weeds have seeds that blow about in the wind just looking for such a place. Other weed seeds can remain dormant for years, imbedded in the soil waiting for some disturbance to bring them to the surface. The best tactic, here, is to keep new plantings weeded religiously plus use plenty of mulch after planting. Once your plantings get out ahead of the weeds you will find less weed growth (refer back to number 1).

3. Weeds prefer poor soils. Remember that Nature’s plan for weeds is to improve soils for better quality plants. I have read and heard many of my gardening colleagues express the opinion that weeds are a sign of an imbalanced soil. Some have gone to great lengths promoting studies to determine the exact minerals or elements that may be missing that in turn can cause certain weeds to grow. This I do not agree with this, to the extent that I have seen most of our common weeds growing in pure compost, not to mention the rich potting soils, that we in the nursery biz take so much care in preparing. On the other hand I have noticed that most fast growing weeds will have a weak, shallow root system when growing on rich, high energy soil. From this I have deduced that weeds do prefer poor soils. Nature has them programmed them to be healthy in a meager environment. Please don’t go off the deep end and expect a totally weed free lawn just because you composted it once or used some organic products. Oh, that gardening were so simple?? You will expect to see a general reduction in weeds, but alas, no miracle.

4. Nothing beats pulling weeds by hand. Don’t get me wrong. There’s plenty of other things I would rather do than pull weeds. The statement is intended to get you to understand that regardless of all the chemical concoctions and mechanical means we have at our disposal, nothing is faster or more cost effective than pulling weeds out by the root. Once accomplished, you have effectively killed that plant, almost instantly, and there is no doubt that it will not grow back although another seedling may take its place.

Weedeaters are a joke. Mechanical tillage works pretty good if you can afford the gas and equipment. Once you stop tilling, here come the weeds!! Even the nastiest herbicides made by the most devious chemical companies only offer short term control. If it were possible to totally eradicate weeds by chemical means these guys probably wouldn’t sell such a product anyway. This is America………….it’s all about resale.

If you read the fine print on these products you will likely find the word “control” instead of “kill,” and you will never read “totally eradicates.” Likewise with the environmentally friendly organic weed killers (there‘s that word again!!). I have tried all sorts of products from soaps and oils to concentrated vinegar and cinnamon. These do a really fine job on annual weeds like henbit or crabgrass but they are no match for firmly entrenched perennial weeds like dallisgrass and nutsedge. I cringe every time someone comes in the nursery looking for something that they heard from some organic guru that supposedly kills nut grass. Again, the operable word is “controls” instead of “kills.”  No treatment I have ever used (chemical or organic) is really 100% effective against nutsedge, but there is a way to beat it.

Referring again back to number 1 on my list, you can beat nutgrass by shading it out. Look under the dense shade of your shrubs. Nutgrass may be present just a few feet away in your lawn but you will not see it in dense shade. You can bet it is likely that underground nuts are there. Remove the shrub or tree and nutgrass will be the first thing up! If present in the lawn, simply raise your mowing level and concentrate on making your grass healthy and dense. Eventually the nutgrass will simply cease to come up. I read an article once that nutgrass can remain dormant for 50 years or more, just waiting for  sunlight to warm the soil which signals the nut to begin growth. I suspect that this may actually be true.

5. Weeds can be useful. Getting back to my earlier statement, weeds do have a purpose in Nature. They are here to take over disturbed areas and improve poor soils. Never lose sight of that. Unless weeds are actually crowding out your desirable plants, it may be to your advantage to allow them to grow at least until you have other plans for that area.

This is the tactic I have chosen to use this year in my vegetable garden. Since I lack the time or inclination to try to control them during this wet year, I have opted to make them useful. How well will it work? I’ll have to wait until next year to find the answer.

I do hope you noticed that I did not mention any type of spray, powder, or special type of fertilizer as a solution in this article. These things do work, but only for the short term and only by percentage. For the long term, pull’em out, shade’m, muclh’em, or mow’em and by all means improve that soil for better quality plants. You will have less weeds.

I own a nursery and we grow lots of plants. Because we are constantly working with disturbed soil, we get more than our share of weeds. I have yet to find a faster or more cost effective weed control than an employee with good work ethic and a diligent eye. If there were a better method, I would be among the first to know………..Wooden eye???

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