Turf generally can be improved through proper mowing, fertilizing, watering, and pest control applications. With some turf problems, however, the only solution is reestablishment, using one of two methods.
The first is the conventional method, which involves destroying the sod, tilling the soil, and replanting. The second method is renovation, which involves replanting without completely tilling the soil and often without destroying all existing vegetation.
Turf areas are often renovated for several reasons. These include:
>Change grasses to plant an improved variety or a more adapted grass.
>Eliminate weeds by killing grassy perennial weeds with a nonselective herbicide before reseeding or by planting a desirable species that is more competitive with weeds.
>Reduce thatch and/or reseed with a non-thatch forming grass.
>Improve a turf damaged by heavy traffic, white grubs, diseases, drought, etc.
Successful renovation involves selecting the best grass, eliminating competition from other grass or weeds, good timing, and proper seedbed preparation and seeding.
The best time to renovate is now through September. The second best time is mid-February through March. Seedings made in June and July are seldom successful for two reasons: It is difficult to keep enough moisture available for the young seedlings, and summer annual weeds like crabgrass will become extremely competitive.
Reduce competition
Germinating grass seedlings cannot compete with an aggressively growing grass or weed. To reduce or eliminate competition from weeds, you can use one of several tactics.
>One is to use a nonselective herbicide like glyphosate (Roundup Pro, Kleenup) or glufosinate (Finale) to kill all grasses, grassy weeds and broadleaf weeds.
>A second option is to mow the turf as close as possible before renovating.
>The third option is to heavily dethatch or thin the lawn by going across it several times with a lawn dethatcher/verticut machine. In all three methods the resulting dead vegetation will help hold moisture, control erosion, and reduce mud until the grass is established.
Almost no success can be expected if you just broadcast seed on the soil surface. For seeds to germinate and survive, they must have good soil contact. Sometimes a heavy raking will loosen the soil surface enough, but most often the surface is very hard.
Weeds, dead grass, or thatch make raking difficult. Home lawns are best renovated with a dethatching machine that will not only loosen the dead grasses, weeds, and thatch, but will also leave shallow grooves or slits in the soil surface. Seeds falling into these slits are much more likely to germinate and live. The machine may need to cross the area several times in different directions to disturb the surface sufficiently.
After dethatching, evenly broadcast seed at a rate of six pounds per 1,000 square feet for tall fescue or at four pounds per 1,000 square feet for perennial ryegrass. Rake the seed lightly into the seedbed or cross the area again with the dethatching machine.
Small, bare spots in lawns can be renovated without destroying existing grass or preparing the seedbed. Broadcast seed on the soil surface and then cover the seed with about 1/8 inch of topsoil or sand. You can also use a shovel or hoe to remove clump grasses, dead turf, and soil to a depth of inch and then repair the area with sod.
For more information on lawn care, log on to http://www.uky.edu/Ag/ukturf/publications.htm, contact the Franklin County Extension Office, 695-9035 or e-mail Kim.Cowherd@uky.edu and ask for the Lawn Information Package.