Mowing & Watering

1. Mowing too short. Scalping your grass stresses the plant and exposes the soil to sun and weeds. Follow the one-third rule: never cut more than a third of the blade at once, and keep most grasses around 3 inches tall so the roots stay deep and healthy.
2. Watering in the middle of the day. Most of it evaporates before it ever reaches the roots. Water early in the morning instead — the grass dries off during the day, which also helps prevent disease.

Weeds & Feeding

3. Ignoring weeds until they go to seed. One dandelion clock can scatter hundreds of seeds across your yard. Pull or treat weeds early, and keep the lawn thick and tall — a dense lawn is the best weed prevention there is.
4. Skipping fall fertilization. The most important feeding of the year happens in fall, when roots store up nutrients for winter and green-up. Skip it and your lawn wakes up thin, pale, and vulnerable.

Soil

5. Never aerating compacted soil. Foot traffic and time pack soil down so water, air, and nutrients can't reach the roots. A core aeration once a year — ideally in fall — opens it all back up.