Washington State University Recommended Lawn Care

  1. Give your lawn some fertilizer. Lawns provided four slow release rate fertilizer applications of one pound of actual nitrogen per 1,000 square feet will keep lawns green throughout the growing season. A 3-1-2 fertilizer ratio of nitrogen (N), phosphorus (P2O5), and potassium (K2O) is best. Recommended fertilizing times are April, June, September, and November/early December. The addition of moss control products with iron as the active ingredient will also help provide a deep green lawn.
  2. Raise mowing height. Mowing height affects water use. Using a higher mowing height deepens root systems, strengthens lawns and reduces water loss through evaporation.
  3. Control thatch build-up. When thatch is greater than one-half inch dethatching is needed. This is best done in early spring or early fall.
  4. Aerate compacted surfaces. Heavy use areas and compacted soils should be aerated providing improved water absorption and air flow within the lawn. Again, spring and fall are the best times for aerating.
  5. Improve your soil by topdressing. This means spreading a thin layer of soil, not more than one-half inch, over an existing lawn/top soil. WSU recommends at least six inches of settled topsoil to maintain a healthy lawn.
  6. Water sparingly. A healthy lawn only requires about one inch of water per week, including natural precipitation. Deep watering once or twice per week is best and encourages deep root growth. Generally, depending on the type of sprinkler you use, a total of 60 to 90 minutes of irrigation per week will provide necessary water for healthy lawns. This watering can be broken into two sessions of 30 to 45 minutes each for lawns that may be lacking sufficient top soil to retain water from weekly irrigation. A tuna can is a simple way to measure watering amounts. Place the can on the lawn and water until the can is half full for twice a week watering or full for weekly irrigation.
  7. Water during cooler times of day. Water either late in the evening (after 8:00 p.m.) or early in the morning (before 10:00 a.m.) This reduces the likelihood of fungal infections, reduces moss growth, and minimizes evaporation. On warm days, if you are watering during daylight hours as much a half of the water evaporates before it reaches your lawns roots!