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Weeds Got You Down?

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August 7, 2006

Not long ago, white clover was considered a fashionable lawn plant. Pleasant to look at, increased the nitrogen content of soils and helped to break up compaction. But since it didn't look like grass, it was classified as a weed. Today, as homeowners reconsider their definition of lawn weeds, clover is slowly regaining its status as a desirable lawn plant. But a weed is really best defined as a plant growing where you don't want it.

Because weeds are survivors, designed to make a go of conditions that don't favor most other plants, they will always be with us, looking for a chance to get established. Rather than cast a disparaging eye on anything growing in the lawn other than your chosen lawn grass, you are better off accepting that diversity is a fact of nature. Your task is to decide which weeds you can tolerate and which must go, whether because they are too noticeable, overly aggressive, or a health hazard, like poison ivy. What can you do?

This is a game of competition. You want to make things favorable for the grass and unfavorable for the weeds so the grass will choke out the weeds. Naturally.

Must do:

• Mow High - Set your mower as high as it will go (3 to 4 inches). If the grass doesn't shade the weed, the weed will shade the grass.
• Water Infrequently - Grass roots are down deep and most weed roots are near the surface. Water only when your grass shows signs of drought stress (it will start to curl) and then water deeply (put a cup in your sprinkler zone and make sure the sprinkler fills it with an inch of water). The idea is to keep the top three inches of soil as dry as you can for as long as you can.

Optional:

• Grass is a nitrogen pig. When mowing, be sure to leave the clippings on the lawn. It adds organic matter and nutrients to help build your soil. If your lawn is in serious need of fertilizer, use phosphorus free fertilizer, apply it at the beginning of fall, and use only half of what the package recommends. Fertilizing in the summer feeds the weeds, not the grass!

MYTH: "If I mow short, it will be longer until I have to mow again." False! Your grass needs grass blades to do photosynthesis (convert sunshine into sugar) to feed the roots. When you whack the blades off, the grass has to RACE to make more blades to make sugar. It then grows amazingly fast. This fast growth uses up a lot of the grass's stored sugar, and weakens the plant. It is now vulnerable to disease and pests! Tall grass is healthier and can use the extra sugar to make rhizomes (more grass plants) thus thickening the turf.

EXTRA TIP: If you have a serious weed infestation, consider mowing twice as frequently as you normally do. The sensitive growing point for grass is near the soil. The sensitive growing point for most weeds is near the top of the plant. So when you mow, it's as if you are giving your grass a haircut and cutting the heads off of the weeds.

For additional information about low-impact lawn care alternatives, check out YardScaping for a Healthy Maine: www.yardscaping.org. YardScaping hopes to inspire Maine people to create and maintain healthy landscapes through ecologically based practices that minimize reliance on water, fertilizer, and pesticides. The Maine YardScaping Partnership was formed out of the rising concern among statewide organizations and agencies over the possible pollution caused by yard care chemicals washing away into water bodies, as well as the risks of pesticide exposure to people, pets, and wildlife.

Ê Tamara Lee Pinard
Senior ProjectÊManager
Cumberland County Soil & Water Conservation District
35 Main Street
Windham, MEÊ 04062
Tel:Ê 207-892-4700
Fax:Ê 207-892-4773
tamara@cumberlandswcd.org