Source: Rick Durham, extension professor, UK Department of Horticulture

 

Many lawns in this area are planted with cool-season grasses including Kentucky bluegrass, tall fescue, perennial ryegrass and fine fescues. They typically withstand cold winters, but each summer their growth slows. But a few simple steps can revive them in late summer.

You’ll often see lawns planted with these varieties begin to brown out in the summer. This is the time to raise that mower deck, because short mowing heights promote shallow roots, which makes it harder for the plants to access water and nutrients in the soil. Cutting your grass at a height of 3 or 4 inches will help promote deeper roots, as well as allow the grass to out-compete weeds, such as crabgrass. Research has shown that tall fescue lawns mowed at 3 or 4 inches will naturally inhibit 85% to 100% of crabgrass germination.

Though a healthy lawn requires little irrigation during ideal weather conditions, during times of drought, lawns may require a little help in this area. There are two thoughts to this. You could choose not to water at all. Kentucky bluegrass will go drought-dormant, but it will green up when it receives rain. Tall fescue has a deep root system and can usually continue through a drought. However, if the drought is too sustained, grasses may not emerge from dormancy. And a drought-dormant turf cannot compete against weeds.

The best practice is to water infrequently but thoroughly. A daily or periodic light watering will only develop a shallower root system. Wait until the lawn is dry enough that you leave footprints. This indicates that the lawn is just beginning to wilt. Water until puddles begin forming on the surface. At this point you have reached the maximum percolation rate of the soil. Don’t water again until the soil dries and footprints are once again visible. This practice will create the deepest possible root system and the healthiest plants in terms of drought tolerance.

It is best to water lawns in the predawn hours. Watering in early morning will greatly reduce losses to evaporation. And remember, excessive watering is every bit as bad as not watering enough. Water will fill up the air spaces in the soil. Roots require oxygen to grow, and shallow roots will result from low soil oxygen levels.

Autumn is the best time to supply nutrients to lawns in Kentucky. Many soils in Eastern and Central Kentucky have adequate levels of phosphorous and potassium, so only nitrogen will be needed. Applying phosphorous and potassium when not needed is a waste of money and can damage the environment. Conducting a soil test every three to five years is a good way to provide your lawn with the nutrients it needs.

Nitrogen applied in the autumn results in better winter color, less frequent spring mowing, fewer weeds, less disease pressure and less heat stress in summer and less water required in summer due to a more extensive root system. Following an appropriate fall fertility program can greatly reduce the need for additional environmentally unfriendly inputs such as herbicides, fungicides and, most especially, water.

Autumn is the ideal time to plant a cool-season lawn, with the best chance of success being from mid-August until the second week of September. Temperatures are cooling down, and there is less competition from summer annual weeds such as crabgrass and goosegrass. Planting in the autumn gives the grasses six to eight months to mature and develop a deep root system before the onset of the summer stress period.

A little care in August and September this year will provide you with a lawn that requires less maintenance next year.

For more information about lawn care, contact the (COUNTY NAME) office of the University of Kentucky Cooperative Extension Service.

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