Volume 16, Issue 23 - June 5 - June 11, 2008



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The Bay Gardener by Dr. Frank Gouin


Feed Your Lawn What It Needs When It Needs It

Spare your lawn over-fertilizing to save money and the Bay

Weed-and-feed fertilizers may sound like a good idea. But using these chemicals on bluegrass and fescue lawns will work against you. Bluegrass and fescue turf grasses are cool-season grasses, meaning they absorb most of their nutrients in the fall as soils cool. That’s why the University of Maryland recommends fertilizing turf grass in late September, October and early November.

Fertilize at the rate of one pound of nitrogen per 1,000 square feet (equivalent to 10 pounds of 10-6-4 fertilizer per 1,000 square feet). At this optimum level, nutrients will be absorbed by the roots, with minimal loss of nutrients by leaching or surface run-off. Fall fertilizing encourages these grasses to develop deep and extensive roots and accumulate and store nutrients for spring growth.

The weed killers added to weed-and-feed fertilizers are designed to kill broadleaf weeds such as dandelions and plantain. Such weed killers are most effective in the spring, when the weeds are most susceptible.

But that’s also when the grasses are growing. So by applying weed-and-feed fertilizers in the spring, you encourage lush succulent top growth of grasses on a limited root system. That kind of growth makes cool-season grasses susceptible to wilt-causing diseases.

So while killing the broadleaf weeds and temporarily making the grass deep green in color, weed-and-feed fertilizers also encourage diseases such as fusarium.

If your lawn has weeds and they are not being controlled by mowing your lawn tall, consider spot spraying with a 2-4,D spray. I can assure you that once the weeds are killed, they will not return because your well-nurtured turf will crowd out all new weeds.

A thick, lush lawn can be cultivated by following a few simple rules. First, set your lawn mower to cut the grass to a height no less than 31⁄2 inches high. Mow the lawn often enough so that you do not remove clippings longer than two inches. Allow the grass clippings to remain and filter down to the ground, where they will decompose and return their nutrients back to the soil for recycling.

Second, fertilize your lawn with a single application of 10-6-4 fertilizer at the rate of 10 pounds per 1,000 square feet in early to mid-October. Have your soil tested at least every three years, and add dolomitic limestone accordingly in early spring.

Third, if you are going to irrigate your lawn, apply at least one-half to one inch of water, a tuna fish can-full, weekly through hot, dry weather. Or don’t bother irrigating and allow the grass to go dormant during periods of drought.

Ask Dr. Gouin your questions at frgouin@erols.com. All questions will appear in Bay Weekly. Please include your name and address.

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