In general, lawns should be fertilized about 4 times a year with 1 lb. of nitrogen at each application. Both cool-season and warm-season grasses require 4 - 6 lbs. of actual nitrogen per year. Application rates vary depending upon the formulation and type of fertilizer used and on the turf species.
It is best for the grass and the environment if you divide the amount of fertilizer required and apply smaller quantities more frequently during the active growing season, rather than applying larger amounts less often. To avoid burning your lawn, no more than 1 pound of actual nitrogen per 1000 sq. ft. should be applied each time.
Factors to take into consideration when choosing fertilizer rate and frequency
Shade and drought
Too much nitrogen can be detrimental for shady lawns because it encourages shoot growth over root growth as well as making turf susceptible to disease or traffic injury. Shaded turf only requires half the amount of nitrogen that lawns in the sun require. Fertilize during the spring and fall. For cool-season grasses, only minimum amounts of nitrogen should be applied in the summer. Potassium is more important than nitrogen for shaded lawns and it should be maximized as it makes turf more tolerant to shade. Under drought conditions, apply nitrogen lightly and infrequently to avoid lush growth and reduce the use of water.
A turf species growing on sandy soil will have the same nitrogen requirement as the same species growing on clay soil, but the nitrogen should be applied at lower rates and more frequently on the sandy soil than on the clay soil.
Type of fertilizer
Quick release fertilizers usually last about 4 - 6 weeks and can be applied at 4 - 6 week intervals during the period of active growth. Slow release fertilizers may last up to 8 weeks. Apply at 6 - 8 week intervals during the period of active growth.
Calculate the amount of purchased product you need for a single application depending on your turf grass species.
Learn more about fertilizing your established lawn.