Cool-season Lawns: How Low Should You Go?

This article is taken from the K-State Horticulture Newsletter

We often are asked whether it is good to mow lower in the spring.  The answer is yes and no.  It doesn’t hurt to mow lower than normal the first mowing or two.  As a matter of fact, it can actually speed green-up by removing old, dead grass and allowing the soil to warm up faster.  But the mowing height should be raised to normal after the first or second cutting to discourage crabgrass.  Crabgrass seed must have light to germinate, and a high mowing height will shade the soil.  Also, root depth and mowing height are related on upright growing grasses such as tall fescue and Kentucky bluegrass — the higher the height of cut, the deeper the root system.  A deeper root system means a more drought- resistant turf.  So, how low should you go on the first cutting? On tall fescue and Kentucky bluegrass, you should mow at about 1 to 1½ inches. Be careful you don't go so low that you scalp the turf.  Normal mowing height for Kentucky bluegrass is 2 to 3 inches and for tall fescue is 2½ to 3½ inches.

Written by Ward Upham, KSU Dept of Horticulture