When you've put in a new lawn, timing of the first mowing can be an important consideration. If you don't mow it soon enough, it may get off to a poor start; if you mow too soon, it may not get started at all. Fortunately, turf experts have some helpful mowing tips to get your lawn off to a healthy start
Don't Wait Too Long
If you wait too long to mow, you've committed the fourth most common mistake when planting a new lawn, according to Nick Christian's list in "Fundamentals of Turfgrass Management." When to mow is determined by the height of your new seedlings or sod, and the "go ahead and mow" height should be about one-and-a-half times the recommended height, according to the University of California. That height depends on the turf grasses you're growing. Homeowners should maintain cool season grasses, such as bluegrass and tall fescues, taller than warm season grasses, such as Bermuda and zoysia grasses.
Given the recommendation that you never remove more than 1/3 of a grass blade's length, mow new cool-season grasses when they reach about 3 inches tall, and warm season grasses when they reach 1 1/2 to 2 inches. Keep new cool season lawns mowed to 2 inches to help thicken them, and warm season lawns at 1 to 1 1/2 inches to help them spread.
Don't Mow Too Soon
"Scalping" new turf by mowing it before it attains enough height, or cutting off more than 1/3 of the grass blades' length, will damage the new root system.
Make Sure Conditions are Right
If the ground is too wet, or you or your mower is too heavy, mowing may leave ruts in your new lawn. Test the ground by taking a few steps on your new lawn, advises Penn State turfgrass science professor Peter Landschoot; if the sod or seedlings spring back, you can mow, if not, wait. Stop watering for a day or so to firm up the ground.
Maintain the Right Mower
When you do mow, use a lightweight mower on new lawns; this is not the time to try out a new riding lawn tractor. Be sure mower blades are sharp. Kansas State University turfgrass specialist Matt J. Fagerness advises that mowing is good for new lawns, unless you use dull blades, which tear grass leaves. He notes that lush, new growth tends to stick to the blades, so mowing when it is warm and dry, preferably in the afternoon or evening, is best for your lawn and your mower.