Now that lawns are greening up, it’s time to consider best practices for mowing your grass.

“How you mow is important,” advises Henrico Extension Agent Karen Carter. “One of the best ways to prevent weeds in your lawn is to mow correctly.”

Start by checking the blade on your mower. It needs to be sharp so that you don’t chew off or shred your grass, which makes it vulnerable to disease and attacks by insects.

The blade needs to be set high enough to leave grass at least 3 inches high. “This is probably the most important thing,” said Carter. “Mowing high improves root growth and helps shade out weed seedlings. You’ll still have some weeds, but the number will be greatly reduced.”

Carter advised following the one-third rule: never remove more than 1/3 of the height of your grass at one time.

Mow regularly, though not when grass is wet, and rotate mowing patterns. And leave the grass clippings on the lawn. As long as they’re not in clumps, grass clippings will decompose and return valuable nutrients and water to the soil. “Lawn clippings are ‘free fertilizer,” Carter said, “and they don’t contribute to thatch buildup.”

Tall fescue grasses, used most often in this area, don’t develop thatch layers.

Tall fescue is a cool season grass that looks good in the spring, early summer, and fall, but it can go dormant in the heat of the summer unless it is watered.

“Lawn irrigation is an all or nothing proposition,” said Carter.

Lawns that aren’t watered can survive as long as they have a strong root system. To keep grass green in summer’s heat, an inch of water is needed every week.

“That means a good, deep soaking that builds the root system,” said Carter. “Not just 15 minutes.”

“The roots are the root of the matter,” she added. “Healthy lawns have strong root systems.”

Applying a broadleaf weed killer should be done now before the weeds get too large. “Spot spray what you’re seeing,” said Carter. Spot spraying rather than broadcasting means you use less weed killer, save money, help the environment, and lessen your exposure to herbicides.

And, if you haven’t already put down a crabgrass preventer, Carter said you can still benefit from applying it. Choose a product that doesn’t contain fertilizer.

“Cool season grasses should be fertilized in the fall,” said Carter. “In spring, fertilizer makes grass put on more top growth – which you don’t need. You’re already mowing in spring, and fall fertilizing promotes root growth.”

Henrico Extension offers the SMART Lawns program to help homeowners have beautiful lawns. Master Gardeners collect lawn soil samples and measure total lawn area, and after processing, homeowners can get customized advice. To learn more, call 501-5160 or search SMART Lawns on Henrico County’s website at http://www.co.henrico.va.us.