When to First Mow After Seeding New Grass

Time Frame

• Do not mow your newly planted grass until it is at least one-third taller than the recommended height for mowing, the Virginia Cooperative Extension recommends. For example, if the recommended mowing height is 2 to 2 1/2 inches, it should be mowed when it is between 2 3/4 and 3 1/2 inches.

Mowing Instructions

• For its first mowing, do not cut more than one-third of the total blade height from the grass, the Iowa State University Extension suggests. Be sure your mower's blade is sharp before cutting your lawn for the first time.

Modifications

• If your newly planted grass surpasses the recommending height for its first cutting, you will need to take special precautions. In these cases, cut the grass in stages so as not to remove more than one-third of the blade height, the Iowa extension advises. Wait at least a few days between mowings.