Angie's How To Fertilize the Lawn

Warm season grasses grow primarily in the South and turn brown in the fall after the first frost. The best time to fertilize warm season grass (such as Bermuda, Carpetgrass and St. Augustine) is summer.

Cool season grasses, which include bluegrass, ryegrass and fine fescue, grow in the northern parts of the U.S., and stay green year-round. For optimum health, these grasses need fertilization in early spring and possibly twice in the fall — once in mid-September with a high nitrogen fertilizer to strengthen blade growth and again in November with a high phosphorus fertilizer to promote root growth.

With your lawn’s dimensions in hand, along with the results of your soil’s pH test, head to a garden center or hardware store to purchase fertilizer. Read the labels on the fertilizer bags carefully to make sure they’re compatible with your grass type. Also pay attention to the three-digit formula code (often called NPK) on the bag, which tells you how much nitrogen (N), phosphorus (P), and potassium (K) the mix contains.

For example, a bag marked 16-4-8 contains 16 percent nitrogen, 4 percent phosphorous and 8 percent potassium. “Check your soil sample to make sure that your turf even needs that much nitrogen,” Schmauder says. “Most homeowners don’t know that you can damage your turf with too much fertilizer.”

Watering after fertilization is important. “Fertilizer should be watered thoroughly to move the product down to the roots where the plant can take it in,” Heiner advises. “A good 30- to 45-minute soaking will do.”

If rain is forecasted in the near future, that will suffice. However, if kids or pets will use the lawn soon after treatment or temperatures are above 85 degrees (which can increase the chances of fertilizer burning the lawn), water the lawn shortly after fertilizing.