Bermuda grass is a warm-season turf known for its heat tolerance and dense growth habit. It enters dormancy, turning straw-brown, when temperatures drop in the fall and winter. The spring transition requires specific attention to encourage a healthy, vibrant summer lawn. Successfully moving the lawn from winter dormancy to active growth involves precise timing and a unique mowing technique that maximizes the grass’s aggressive growth potential.
Identifying the Right Time for the First Cut
Determining the precise moment for the first spring mow depends entirely on the soil temperature, not the calendar date. Bermuda grass initiates green-up when the soil temperature, measured at a four-inch depth, consistently reaches 55°F. Vigorous, sustained growth begins when that temperature climbs to a consistent 60°F to 65°F. Monitoring this specific depth with a soil thermometer is the most accurate approach to timing the first cut.
Waiting until the soil has warmed sufficiently ensures the grass has the energy reserves to recover from the aggressive initial mowing. A visual cue that the time is approaching is a “light green haze” across the turf, indicating new shoots are emerging from the dormant runners. Mowing before the soil is warm enough can delay the full transition. The goal is to perform the first cut after the danger of a hard frost has passed, just as the new growth begins.
The Crucial First Mow: Scalping
The first spring mow is a specialized technique called scalping, which is the intentional removal of the majority of the dormant, dead material. Scalping involves setting the mower to its lowest possible setting, typically between 0.5 to 1 inch, to aggressively cut away the brown winter canopy. This process removes accumulated dead leaf and stem material from the previous season, preventing a dense layer of thatch.
Removing the dormant material serves several biological functions for the turf’s recovery. Eliminating the tall, brown layer allows the sun’s energy to reach the soil surface, significantly warming the ground. This rise in temperature stimulates the underground runners (rhizomes) to push out new lateral growth, leading to a faster and denser green-up. It is imperative to bag or collect all the clippings to prevent debris from smothering new growth and creating an excessive thatch layer.
Setting Maintenance Mowing Heights
After scalping, the lawn will appear short and thin. The mower deck should then be raised to a moderate summer maintenance height. For most residential lawns using a rotary mower, this height is maintained between 1.5 and 2 inches to balance health and appearance. Maintaining the grass at this low height encourages Bermuda grass to grow horizontally, creating the dense, carpet-like turf it is known for.
Once the grass is actively growing, adhere to the “one-third rule” for all subsequent mowing sessions. This rule dictates that no more than one-third of the grass blade height should be removed in any single cut. For example, if the desired maintenance height is 1.5 inches, mow before the grass reaches 2.25 inches tall. Following this principle prevents stress on the plant, which could inhibit root growth and leave the lawn susceptible to disease and heat stress.
Post-Mow Fertilization and Watering
Following the scalping, correctly time the application of nutrients and moisture to fuel the new growth. The first spring application of fertilizer should be delayed until the Bermuda grass is fully greened up and actively growing, corresponding to consistent soil temperatures reaching 65°F to 70°F. Applying nitrogen fertilizer too early, while the grass is still vulnerable, can encourage a flush of growth that an unexpected late frost could damage.
The timing of pre-emergent herbicide application must also be addressed relative to the spring warm-up. These herbicides prevent weed seeds from germinating and should be applied when the four-inch soil depth consistently reaches 53°F to 58°F to target weeds like crabgrass. This temperature is often reached well before the ground is warm enough for the aggressive scalping mow, making weed control an earlier step. After scalping, the lawn requires generous watering to aid recovery, ensuring the exposed soil and runners have enough moisture to support new root and shoot development.