Lawn Care Guide: Mowing, Watering, and Feeding
A plain-English lawn care guide: how high to mow, how much to water, when to fertilize, and how to keep weeds out.
Header Photo: Shixart1985 / Wikimedia Commons, CC BY 2.0
Healthy lawns come from three habits: mow high, water deeply but not often, and fertilize at the right time for your grass type. Get those right and most weed and disease problems shrink on their own.
Know your grass type first
Almost every lawn care decision depends on whether you have cool-season or warm-season grass.
- Cool-season grasses (tall fescue, Kentucky bluegrass, perennial ryegrass) grow most in spring and fall. They’re common in the northern half of the U.S.
- Warm-season grasses (bermudagrass, zoysia, St. Augustine, centipede) grow most in summer and go brown and dormant in winter. They’re common across the South.
Not sure which you have? Your local cooperative extension office can identify it, often for free.
Mowing: the one-third rule
Never cut off more than one-third of the grass blade in a single mowing. Cutting more stresses the grass and opens space for weeds. If the lawn gets too tall, bring it down gradually over a few mowings.
| Grass | Typical mowing height |
|---|---|
| Tall fescue | 3 to 4 inches |
| Kentucky bluegrass | 2.5 to 3.5 inches |
| Bermudagrass | 1 to 2 inches |
| Zoysia | 1 to 2 inches |
| St. Augustine | 2.5 to 4 inches |
| Centipede | 1 to 2 inches |
Recommended heights vary a little by variety and region, so check your local extension guide. Two more mowing habits pay off fast:
- Keep the blade sharp. A dull blade tears grass instead of cutting it, leaving ragged brown tips.
- Leave the clippings. Short clippings break down quickly and return nutrients to the soil. They don’t cause thatch.
Watering: deep and infrequent
Most lawns need about 1 inch of water per week, including rain, during the growing season. Water deeply once or twice a week instead of a little every day. Deep watering grows deep roots that handle heat and drought better.
- Water early in the morning. Less water evaporates, and the grass dries off during the day, which lowers disease risk.
- Measure it. Set a few empty tuna cans on the lawn and run the sprinkler until they hold about an inch.
- Don’t overwater. Frequent shallow watering keeps roots near the surface, wastes water, and can encourage disease.
Feeding: fertilize for your season
- Cool-season lawns: fall is the most important time to fertilize, when roots are actively growing.
- Warm-season lawns: fertilize after the lawn fully greens up in late spring and through summer. Avoid feeding while it’s dormant.
Before you buy fertilizer, get a soil test. Most extension offices offer inexpensive tests that tell you exactly what your soil is missing, so you don’t pay for nutrients you don’t need. Always sweep fertilizer off driveways and sidewalks so it doesn’t wash into storm drains.
Weeds: prevention beats spraying
A thick lawn mowed at the right height shades out most weed seeds. For crabgrass, a pre-emergent applied in early spring, roughly when soil temperatures reach about 55°F, stops seeds before they sprout. Many gardeners time it to when forsythia shrubs bloom. For a few scattered weeds, pulling them by hand is often faster than any product.
Aeration and thatch
If water puddles or the soil feels hard, core aeration pulls small plugs of soil to let air, water, and nutrients reach the roots. Aerate cool-season lawns in early fall or spring, and warm-season lawns in late spring or early summer, when each is growing strongly.
See exactly when to do each job on the seasonal lawn care calendar.