Uninvited Guests


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Weeds are uninvited guests. They arrive unannounced, take up space, consume valuable assets (like water and soil nutrients) and just won’t leave, despite our best efforts. A colleague of mine thinks they could be beneficial plants, but we haven’t figured out what that benefit could be. I used to feel that way until I began spending hours pulling out these unwelcome plants. I know they’re plants out of place, but the place they should be is anywhere but my garden. 

Some of these are particularly problematic, especially if they’ve become established.  Not only can they injure desirable plants and remove precious resources, but some of them can poison the soil with salt or even toxins, and then there are the others that strangle tender plants. Many of them reproduce amazingly quickly, either through massive seed production or through asexual methods, like little nutsedge tubers.

The easiest way to deal with a weed problem is to catch it before it gets too big. Pulling small weeds before they produce seeds or underground organs – that’s the best.

Pulling and digging them out while they’re still young keeps them to a manageable level. Too bad we seldom notice weeds until they’ve arrived in legions. Some, we don’t even detect until they’ve flowered. Flowers mean seeds. Seeds mean more unwelcome plants, especially with annual weeds.

Support comes from

Happily, for annuals, a layer of mulch can be a decent form of weed control. By blocking light from getting to the seeds, you’re preventing most of them from germinating. Of course, you’ve got to keep the mulch on through the growing season.

Corn gluten meal isn’t corn meal; it’s a by-product of corn syrup manufacturing. Spreading a layer of this on the soil before seeds sprout is very effective at preventing germination. Don’t bother if the seeds have already emerged, though; it doesn’t work on them.

If you’re unfortunate enough to have annual weeds that did germinate, try to kill them before they flower. Mowing and mulching are pretty effective.

Perennial plants, the ones that’ll flower and go to seed for years on end, they’re another story. Different weeds require different kinds of control. When I say control here, I mean things like putting shade over them to slow down their growth or cutting them down just as they begin to bloom. That’s supposed to weaken the weed after a few years.

Sometimes, though, you’d prefer that they were gone, quickly. Herbicides were designed for this. Americans use more herbicides than any other pesticide – far more than insecticides. We have so many herbicide choices, organic and conventional. I don’t say “weed killers”; the chemical can’t differentiate between the plant you want and the one you want gone.

Spraying annual weeds that’ve already bloomed is a big waste of time and money. Once annuals produce seeds, they’re going to die on their own. Not that you can’t get a feeling of satisfaction seeing them gone, but it’s silly.

Organic herbicides are usually what’re called “burn down”. Things like horticultural vinegar do just that. You spray the plant thoroughly and all the above ground part of that weed dies. It doesn’t affect the roots or any below ground structures, but if the root system isn’t too huge, the plant’ll die.

When you’ve reached the point where conventional herbicides seem to be the only answer, you’ll want to be very careful, especially when temperatures are 90° or more, or if the wind’s blowing. Take a careful look at the label on the container; it’ll probably give a maximum temperature.

If you spray when it’s too hot or windy, you’ll wind up not only spraying your own weeds, but you might be damaging your neighbor’s garden.

You might also be hurting yourself. Pesticide poisoning can produce some of the same symptoms you’d develop from excess heat.  A number of herbicides also cause nausea or dizziness, especially if the person applying them gets careless.

Warm weather means getting into the garden but it also means weeds. Control them safely and early; your garden will love you.

For KNPR’s Desert Bloom this is Dr. Angela O’Callaghan of the University of Nevada Cooperative Extension.

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