Bermuda grass is a popular warm-season turfgrass known for its heat and drought tolerance, making it a common choice across the Southern United States and the Transition Zone. During colder months, this grass enters a state of dormancy, a natural survival mechanism where the plant conserves energy. The grass turns a tan or straw color, halting its growth until environmental conditions are favorable again. Accurately predicting the end of this dormant period is challenging because the timing is highly variable, depending not on the calendar but on local climate patterns.
The Temperature Trigger
The true signal for Bermuda grass to exit dormancy is not a brief warm spell in the air, but a sustained warmth in the soil where its roots reside. Green-up typically begins when the nighttime air temperatures remain above 60°F for several consecutive days. However, the most reliable indicator for active growth is when the soil temperature at a four-inch depth consistently exceeds 65°F. Temporary periods of warm air in late winter often cause a false start, where the grass may show slight greening only to be damaged by a subsequent late frost. This dependency on soil temperature means that lawns in the deeper South will emerge from dormancy weeks earlier than those located in the cooler Transition Zone.
Pre-Emergence Preparation
Preparation for spring should begin well before the grass fully breaks dormancy to ensure a dense, weed-free lawn. One of the first physical tasks is scalping, which involves mowing the lawn down to a very low height, typically around a half-inch. This removes the dead, dormant leaf material, allowing sunlight to penetrate the soil and warm it faster, which encourages an earlier and more uniform green-up.
This is the optimal time to address soil compaction with core aeration, which pulls small plugs of soil from the ground to improve air and water movement to the roots. The most time-sensitive task, however, is the application of a pre-emergent herbicide to prevent warm-season weeds like crabgrass. Pre-emergent must be applied before weed seeds germinate, which happens when the soil temperature at the surface consistently reaches 55°F.
Applying the herbicide at the 55°F soil temperature window creates a chemical barrier that stops weed seeds from sprouting while the Bermuda grass is still mostly dormant. Waiting until the grass is fully green often means the primary weeds have already germinated, rendering the pre-emergent ineffective. This early action prevents competition and allows the Bermuda grass to dedicate its energy to healthy summer growth.
Managing the Green-Up Phase
Once the grass begins its transition, care shifts from preparation to supporting new growth. Initial watering should be conservative, as the grass has low moisture needs while still mostly dormant. Once the blades show active greening, the lawn benefits from deep, infrequent watering to encourage strong, deep root development.
It is advisable to delay the first heavy nitrogen fertilization until the lawn is at least 75% green and actively growing, typically around mid-to-late spring. Applying high-nitrogen fertilizer too early can suppress root growth, feed cool-season weeds, and promote weak growth vulnerable to late frosts or spring diseases.
It is common to see a patchy green-up, where sunny areas or spots near heat-retaining structures green up first. Resisting the urge to apply extra fertilizer to these areas is important, as it will not speed up the recovery of the rest of the lawn. Continuing to mow at a slightly lower height during this transition helps remove the last of the dormant material and promotes a denser, more uniform canopy as the Bermuda grass fully awakens.