When Should You Dethatch Your Lawn in Florida?

Timing

• Dethatching causes a fair amount of damage to the grass, so do it when the grass is actively growing and will have time to recover before the dormant season. Try to time the procedure for when you anticipate at least 45 days remaining in the growing season and no hot, cold or dry spells are expected. According to the University of Florida, the best time to dethatch a lawn with warm-season grasses north of Orlando is April through July, while lawns in areas south of Orlando recover best if dethatched between March and August. Cool-season grasses recover from dethatching best in early fall or early spring.

Measuring Thatch

• The best way to determine if your lawn requires dethatching is to measure the thickness of the thatch layer in several spots throughout the yard. Use a hand spade to dig up wedges of soil and grass about 3 inches deep. Measure the brown thatch layer between the soil surface and the bottom of the green portion of the grass. If the thatch layer is more than 1/2 inch thick, dethatching will benefit the lawn.

Other Maintenance Practices

• Dethatching is often most effective performed with a few other lawn maintenance tasks, in the correct order. Prior to dethatching, cut the grass slightly lower than usual. Following dethatching, rake up all debris and aerate the lawn if the soil is compacted. Fertilize the lawn with a complete fertilizer at a rate of 1/2 to 1 pound of nitrogen per 1,000 square feet, and water the grass deeply and infrequently to encourage recovery and root growth. Apply any preemergent herbicide or overseed the grass to correct any thin or bare spots following dethatching, aerating and fertilizing.

Slowing Thatch Accumulation

• Whether your lawn consists of very vigorous, spreading grass species that usually require annual dethatching or slow-growing bunch-type grasses that rarely need dethatching, proper care practices slow thatch accumulation. Conversely, excessive nitrogen fertilizer applications, infrequent mowing and shallow, frequent irrigation encourage thatch buildup. Occasionally topdressing the lawn -- broadcasting no more than about 1/4 inch of topsoil or compost evenly over the grass -- introduces additional microorganisms to the thatch that help break it down.