Bermudagrass is a warm-season turf grass that grows in home lawns, athletic fields and golf courses throughout the southern United States. The dark green grass adapts to a variety of soils and climatic conditions, tolerates drought and withstands foot traffic. Bermudagrass grows rapidly and readily recovers from injury because it spreads by ground stems, called stolons, and underground stems, called rhizomes. The stems produce a dense lawn that can spread to garden beds and walkways. There is no prescribed method to thin bermudagrass, but the grass will eventually decline and thin out without proper maintenance.
Increase the amount of shade the lawn receives. Bermudagrass needs light to carry out photosynthesis and develop long running stems. Plant new trees and stop pruning established trees. The resulting shade will hinder stem formation and impact grass growth.
Mow bermudagrass high and infrequently. Set the mower to the highest setting to allow the grass to remain tall. Tall grass leaves prevent light from reaching the base of the plant, and so decreases vigor. Frequent mowing encourages re-growth as the grass taps the energy of the underground stems to compensate for blade loss during cutting.
Allow thatch to develop in bermudagrass. Thatch is a layer of vegetative matter that naturally develops between the grass leaves and the soil. Thatch accumulation prevents air, nutrients and water from entering the soil and causes plant stress, which makes the lawn less able to compete with weeds or recover from damage.
Apply a nitrogen fertilizer to thin bermudagrass. Quick-release formulas burn grass plants if applied in heavy concentrations to wet lawn. High nitrogen fertilization applications also increase the susceptibility of bermudagrass to insects and diseases.
Let pests take over the lawn. Bermudagrass mites and mealybugs suck juice from the stems and stunt grass growth. Nematodes cause the grass plant to develop shallow roots that do not receive enough water to maintain fertility.