Cool-Season Lawns Ready for Food

MANHATTAN, Kan. – It's basic biology, even in the landscape: For best growth, things need good nutrition.

Many landscape plants are fairly obvious when they're staging a growth spurt. In the hot-summer regions of the central United States, however, some big exceptions may be the cool-season lawn turfs.

When these tall fescue and Kentucky bluegrass lawns are simply growing taller, they simply need to be mowed, according to a Kansas State University horticulturist. Their nutrition needs spike only when they're also growing larger - sort of sideways (September) or down and out in the soil (November).

"Cool-season grasses naturally thicken up in the fall by tillering, which is forming new shoots at the base of existing plants,” says Ward Upham, who heads the Master Gardener program for K-State Research and Extension. “Bluegrass also spreads then by sending out underground stems called rhizomes. That's why if you're just going to do it once, September is the most important time to fertilize these grasses."

As they use that food through fall, the lawns start to prepare for winter, too - expanding their root system and storing food reserves to help them 1) get through winter, 2) green up early in spring and 3) survive the following summer. So, for best health, they need another meal in November, Upham says.