September has arrived. The heat and drought of summer have left their mark in the history books. Now is the time to turn our attention toward tall fescue and Kentucky bluegrass lawns. The weather has been perfect to fertilize, cultivate and rejuvenate those sickly bare spots in the yard.

Here are some pointers to help get you started with this timely seasonal task:

September is a great time to revitalize cool-season lawns. These grasses are coming out of their summer doldrums and are beginning to grow more vigorously as days shorten and temperatures cool. They naturally start to thicken up by forming new shoots at the base of existing plants. And planted seeds sprout quickly and begin filling in were there is no grass.

There are several steps home owners can take to aid in the revival. Begin with aeration. The two most common aeration methods are power-raking and core-aerating. Power-raking is primarily a thatch-control operation. It can do more harm than good if not done carefully. For mostly fescue lawns or lawns with less than an inch of thatch, I do not recommend power-raking. Thatch is a springy layer of light-brown organic matter that looks something like peat moss and is above the soil but below the grass foliage.

Core-aeration is a much better practice for most lawns. By removing cores of soil, core-aeration relieves compactness, hastens thatch decomposition and improves water, nutrient and oxygen movement into the soil. Make enough passes with the aerator so that the holes are 2 to 3 inches apart and are 2 to 3 inches deep. Turned up cores can be left on the lawn to decompose naturally. Or they can be broken up with a lawn mower set just low enough to nick the cores and then drug with a section of chain-link fence or a steel door mat. This creates a mixture of soil and thatch that is good for the lawn.

If your lawn has been severely damaged from the summer you may want to start over. Soil aeration is just as important in this case and best achieved with a rototiller. Not only does this loosen the soil, but it also turns up weeds and other dead or dormant plant material. After tilling, rake the area to remove clumps of plants, rocks and other unwanted debris. Apply the seed and a seed starter fertilizer. Then, if possible, roll to smooth and firm the surface.

Finally, to fertilize in September, apply 1 pound of actual nitrogen per 1,000 square feet. Aerate first so nutrients penetrate the soil surface. Use a balanced fertilizer that is higher in nitrogen than phosphorous and potassium. Most fertilizers sold in garden centers and discount stores are formulated for a fall feeding and can be used at this time. For more information on fall fertilization, call my office for a free brochure full of tips and an easy-to-use fertilizer calculator.

— Bruce Chladny is horticulture agent at K-State Research and Extension-Douglas County. For more information, call him at 843-7058 from 8 a.m. to 5 p.m. weekdays.