Lawn Coring (Aerification)

Compaction is a physical condition that slowly reduces the amount of air in the soil. Walking, playing and mowing as well as rainfall contribute to soil compaction. Roots need oxygen to grow. As the soil is trafficked, soil particles in the top few inches are compacted into a layer. Compaction is frequently a problem with clay soil. Less air or water can enter the soil. The result is a weaker, thinner turf and more weeds.

Coring will help alleviate this condition. Coring (also called aerating) is the removal of small cores of soil from the top inches of soil to allow nutrients, water, and air to enter the root zone. Use a device that removes soil cores rather than a corer that only punches holes in the soil. The holes left in the turf becomes an avenue for oxygen and water to enter. Root growth around the hole increases and plant vigor is enhanced. Benefits from coring include:

	*	Enhanced water uptake.
	*	Improved fertilizer uptake.
	*	Reduced water runoff.
	*	Enhanced gas exchange.
	*	Enhanced thatch breakdown.
	*	Enhanced heat and drought tolerance.

Coring should be done at a time when the lawn is actively growing so that it can recover from any injury. It is best to core cool-season grasses in fall or early spring. Warm-season grasses are best cored in late spring or early summer. How frequently to core will depend on the extent of soil compaction. Heavy clay soil may need coring every year. Some lawn care and landscape companies offer a coring service if rental equipment is not available.

Sod-forming grasses such as Kentucky bluegrass, bermudagrass, zoysiagrass, St. Augustinegrass, and centipedegrass can build up thatch when they are heavily fertilized and watered. When thatch exceeds 1/2 inch, lawns should be power raked and cored.

A light power raking is better than trying to remove too much debris at one time. When not excessive, thatch buildup can be removed from warm-season grasses by cutting as closely as possible at the time of spring green up, then raking by hand.

To avoid seriously injuring the lawn, a 3 inch blade spacing is required to remove thatch from centipedegrass and St. Augustinegrass. Some lawn care and landscape companies have specialized equipment and offer power raking service.

Consumer Horticulture | Quick Reference