University of Wisconsin - Extension

Autumn is a great time for getting your lawn back in shape following our hot, dry summer. Many lawns have areas that were killed by hot weather diseases like Pythium blight or which failed to recover from prolonged drought. University of Wisconsin-Madison/Extension turfgrass specialist John Stier offers the following tips for caring for your lawn this fall.

By now, lawns should have recovered from summer dormancy, according to Stier. If not, they are unlikely to recover and need to be reseeded or resodded. If a lawn is suffering from other problems (slow growth, weeds, etc.) this is a great time to do something to fix it. The warm soil and daytime temperatures, along with cool night temperatures, provide ideal conditions for turfgrass germination and growth.

Small patches of lawn can be raked out and reseeded. Seed that contains Kentucky bluegrass, with or without perennial ryegrass, is the best choice for most lawns. For shaded sites or low maintenance lawns, choose seed that contains predominantly fine fescues, described on the label as creeping red fescue, hard fescue, Chewings fescue, or sheeps fescue. Either sprinkle the seed on the bare soil, then rake it into the top one-quarter inch of soil, or mix the seed with soil and sprinkle it on the ground. Add a little straw mulch for best results but take care not to overdo it: half of the soil surface should still be visible after mulching.

Large areas of dead lawn may need to be reseeded with a slit seeding machine (farmers call them drills) or in conjunction with core aeration. The idea is to place the seed in contact with the soil.

Core aerators can be obtained from many equipment rental stores. These machines pull plugs of soil, usually two to three inches deep and between a half to one inch diameter, from the lawn. Follow the core aeration by sprinkling seed as described above so that there are roughly 15 seeds per square inch. Use the suggested quantity as shown on the seed label. If there are no instructions, use one to two pounds of seed per thousand square feet if 100 percent Kentucky bluegrass is used; for Kentucky bluegrass/perennial ryegrass and fine fescue mixtures, use four pounds of seed per thousand square feet.

Mow the lawn or drag the lawn by pulling a weighted chain link fence section, box springs, or similar structure around the lawn to break up the soil cores and achieve good seed to soil contact. Slit seeders are available in some areas and accomplish good seed to soil contact by cutting furrows into the ground and dropping seed into the furrow. Many lawn care companies can provide core aeration and/or slit seeding services.

Fall is also a great time to use core aeration to reduce compaction problems. Turfgrasses will grow better if the soil is not overly compacted. Although the core aeration makes the lawn look messy due to the cores laying on the ground, the soil cores quickly disintegrate and the lawn recovers better than before in just a short time.

Fertilize your lawn between late August and mid-September. This should be done even if the lawn has no problem areas. The schedule of holidays is a great way to remember when to fertilize your lawn: Memorial Day, July 4 (unless it's hot and dry), Labor Day and Halloween.

Nitrogen is the most important nutrient for home lawns; phosphorus and potassium are usually in sufficient supply in the soil. Nitrogen is the first number on the label of a bag of fertilizer. Most homeowners should use a fertilizer that contains 20 percent or more nitrogen and little if any phosphorus and potassium. Fertilizer with a ratio of 34-3-3, 27-3-6, 19-4-4 or similar numbers, is a good choice.

For more information about caring for turf, go to the UW-Extension Urban Agriculture and Horticulture Team web site at http://www.uwex.edu/ces/wihort/"> http://www.uwex.edu/ces/wihort.