A lawn containing less than 50% of the desired turf is a candidate for renovating. In some cases, only a few patches need restoring. The best time to renovate a lawn is from mid-August through September. Lawn renovation involves replanting without completely tilling the soil and often without destroying all existing vegetation.
If weeds are growing in the lawn area that you want to renovate, apply a herbicide containing glyphosate (Roundup, Kleenup) that is not selective. Remember that glyphosate kills or injures plants that it touches. It works best when weeds are actively growing. Use the product according to the label directions. Check the product label to make sure the only active ingredient is glyphosate so that grass may be seeded before the end of September.
Depending on the weeds you are trying to control, the herbicide may need to be applied again before planting the seed. For example, when trying to control Bermuda grass, multiple treatments at three-week intervals with glyphosate are needed. Remember, you will have to re-establish the lawn in the herbicide treated area. If you have questions about using a herbicide, please ask before using it. After the final herbicide spraying, wait the number of days listed on the label before planting the seed. Then mow the turf as close as possible before renovating.
Next, prepare the seed bed. Seed will not germinate and grow properly if it is just broadcasted on the soil surface. The seed needs to have good contact with the soil.
If the thatch layer, a layer of tightly intermingled living and dead shoots, stems and roots, is a half-inch or thicker, remove the thatch with a dethatching machine that has knives or blades. Machines with spring tines or mower attachment tines for dethatching are not effective for turf renovation. Pick up the thatch, and remove it from the area before seeding the lawn.
If the thatch is not over a half-inch thick, the dethatching machine would be handy over large areas to remove dead grass and disturb the soil for good seed contact.
Next, evenly broadcast the seed and rake it into the seed bed if you have a small area to renovate, or cross the area again with the dethatching machine. You would apply 6 pounds per 1000 square feet of a turf-type tall fescue variety on a lawn killed with the herbicide.
Keep the newly seeded area watered. In hot, windy weather, one or two light irrigations per day may be needed until germination is complete. Then water deeply and less frequently to encourage a deep root system.
If the thatch was not completely removed, even more frequent watering is needed because it has the tendency to wick the water from the seed and almost eliminate germination.
To thicken a tall fescue lawn with no weed problems, prepare the seed bed with a coring machine that removes 2- to 3-inch long cores of soil from the top and redeposits them on the surface. After making several coring machine passes over the area, seed the lawn. Then drag a section of chain link fence or rake over the area to obtain good seed to soil contact.
Before seeding the lawn, test the soil to determine if lime, phosphate and potash are needed. These can be applied at any time. Testing for nitrogen is not included because science shows that nitrogen is always required by growing plants.
Nitrogen should be applied soon after germination. If nitrogen is applied before seeding, weed growth is encouraged. Apply about 1 pound of nitrogen per 1,000 square feet. Farm-type fertilizers, like urea, need to be applied when the lawn is dry and the weather is cool to prevent burning the grass leaves. Otherwise, the fertilizer will need to be watered in right after it is applied; specialty organic turf fertilizers do need to be watered in but may cost more.
It is important to mow the renovated lawn as frequently as needed to keep the old existing grass from shading the new seedlings. As new seedlings develop, continue mowing at the height intended for the entire area.
Very small bare spots in lawns can be renovated without destroying existing grass. Prepare the seed bed by broadcasting the seed on the soil surface, then cover the seed with about one-quarter inch of topsoil or sand. You can also use a shovel to remove clumps of grass, dead turf, and the soil to a depth of one-half inch and repair the area with sod.
Do not sow the grass seed too thick because it can encourage an environment more favorable for disease development. For more information, contact the Daviess County Cooperative Extension Service at 270-685-8480.
One free soil test for the lawn, garden, or landscape plants in Daviess County is sponsored by the City of Owensboro and Daviess County. Only 50 free tests are available. This saves the cost of $8 for one test.
Enjoy the surprise lilies Lycoris squamigera, also called magic lilies or naked ladies, as they are emerging from the ground. The flower stalk appears without leaves in the fall.
There's still time to sign up for the Extension Master Gardener class, which will meet at the Daviess County Extension Office from 9 a.m. to noon every Thursday beginning Sept. 5. For more information and an application, please call 270-685-8480. Application and fee are due Aug. 16.
Annette Meyer Heisdorffer is the Daviess County extension agent for horticulture. Her column runs weekly on the Home & Garden page in Lifestyle. Email her at email@example.com.