| Control Lawn Weeds Naturally |
Master gardener Joe Lamp'l, host of Fresh from the Garden, suggests a variety of ways to combat weeds in the yard.
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It is important to give newly seeded lawns ample time to mature before applying post-emergent. (SHNS photo courtesy Joe Lamp'l)
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By Joe Lamp'l
March 3, 2008 — Try as you may, weeds are here to stay, and unfortunately you'll never completely eliminate them from your lawn. They find their way into your grass from wind, birds, neighbors, pets and other wildlife. Although eliminating weeds permanently is an exercise in futility, a few ongoing steps listed below will get you closer to your goal. There are many herbicides available to effectively manage weeds in turf. These products are classified into two broad categories, pre-emergent weed control and post-emergent weed control. Pre-emergent weed control These products are designed to inhibit development of the germinating weed seeds from establishing in your lawn. Success depends on the timing of the application. Most weed seeds germinate when soil temperatures reach a certain level. Therefore, the pre-emergent product must be in place before these temperatures arrive. An organic pre-emergent alternative: Corn gluten was patented in 1991 and has gained popularity as a natural alternative to synthetic pre-emergent herbicides. It also has 10 percent nitrogen content by weight, making it an excellent natural fertilizer for established plants with a mature root system. However, when using corn gluten, proper timing and application rates are important for effective control. It should be disbursed four to six weeks before seed germination. First-year reduction of targeted weed populations has at 50 percent to 60 percent success rate. Two to three years of repeated applications are necessary to match the effectiveness of synthetic counterparts. When applying, corn gluten should be distributed at 20 pounds per thousand square feet and no less. It's also important to water just after application so the product reaches the roots where it desiccates them. However, any rain within a couple of days after that may rehydrate the roots and reverse the effects of the corn gluten. Lawn weeds can be either annual or perennial. Annual weeds are further classified as cool- or warm-season types. Pre-emergent should be applied in the late summer or early fall for cool-season annual weeds and again in mid- to late winter for warm-season weeds. Post-emergent weed control The second type of chemical control kills weeds after they have germinated. These herbicides are referred to as "post-emergent." They kill broad-leaf weeds. Some post-emergent products are designed to work only with certain grass types. Read the label; using a product not made for your grass type could inadvertently kill the grass as well. Organic post-emergent alternatives: Organic solutions to post-emergent weed control are all "non-selective" — that is, they kill everything. For the most part, all are effective at burning down top growth. However, long-term control varies depending on the weed and the extent of the root system. In my experience, deep "tap-rooted" weeds are difficult to control with one application. Multiple applications may be necessary. Boiling hot water is effective in killing annual weeds and with repeated use will also kill a number of perennial weeds. Use caution and pour the water from just a few inches above the plant. There are ready-to-use products on the market that incorporate one or more of the following ingredients, which are also non-selective, organic, post-emergent weed eliminators. Look for products containing: Vinegar — (20 percent concentration), clove oil, thyme oil and citric acid. Some words of caution
- Apply herbicides early in the morning or late in the day. Conditions are usually calm at this time. Any wind at all can carry the fine mist onto non-targeted plants and damage them.
- Hot temperatures and direct sun can intensify the killing action of even "selective" herbicides, so much so that it can kill the grass, which otherwise would not be affected.
- It is important to give newly seeded lawns ample time to mature before applying any post-emergent. It is necessary to wait six weeks after grass-seed germination.
If all this sounds like too much to keep up with, I have news for you: weeds aren't necessarily all bad, especially when you keep them from going to seed with proper mowing. Weeds attract beneficial insects, add nutrients to the soil and create biodiversity. And when you're ready to tackle those weeds again without chemicals, cultivation by hand or tools is still the most effective "selective" method because you decide which plants are weeds. (Joe Lamp'l, a master gardener, hosts DIY's Fresh from the Garden as well as a gardening radio show. For more information, visit www.joegardener.com. Distributed by Scripps Howard News Service.) | Get DIY On Your TV. Just follow the instructions to see if DIY Network is available through your cable or satellite provider. |
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