Post-Emergent Applications on Dormant Bermuda: What You Can and Cannot Spray

Dormant Bermuda grass is one of the best opportunities in North Texas lawn care — and one of the easiest to mishandle. From roughly November through March, Bermuda goes tan and dormant across the DFW area, and that dormancy creates a window where certain post-emergent herbicides can be applied to control actively growing winter weeds without fear of injuring the turf underneath. But the window has hard limits. Apply the wrong product, or apply the right product at the wrong time as Bermuda approaches green-up, and you can set your lawn back months. At Hamann Lawn Care & Weed Control, we’ve been managing this window in Tarrant County since 2006, and the details matter enormously.

What Dormancy Means for Bermuda

Bermuda grass is a warm-season perennial that goes dormant when soil temperatures drop consistently below approximately 50°F at the 4-inch depth — in Arlington, that typically happens in late November and the turf remains fully dormant through January and most of February in a typical year. During dormancy, Bermuda’s above-ground growth stops completely and metabolic activity in the crown and root system slows to a maintenance level. The plant is not dead — it is preserving energy in the root system for the flush of growth that will come when soil temperatures rise again in spring.

This metabolic slowdown is what makes dormant Bermuda more tolerant of certain herbicides than actively growing Bermuda would be. Because the plant is not actively transpiring, translocating, or dividing cells, systemic herbicides absorbed through dormant tissue have less capacity to move through the plant and cause widespread damage. The crown and root system are somewhat buffered from what happens on the surface.

What You CAN Spray on Dormant Bermuda

The most important product for dormant-season weed control on Bermuda lawns is atrazine. Atrazine is a photosystem II inhibitor (WSSA Group 5) that provides excellent control of a broad range of winter annual broadleaf weeds and some grassy weeds, including:

• Henbit — the most visually dominant winter weed in Arlington, with purple flowers covering lawns in late winter. Atrazine applied in December to January controls henbit both pre-emergently (preventing germination of seeds that haven’t yet sprouted) and post-emergently on young plants.
• Chickweed — a low-growing, mat-forming winter annual that thrives in moist DFW winters. Atrazine provides reliable control on young chickweed before it matures.
• Annual bluegrass (Poa annua) — the thin-bladed grassy weed that turns golf courses and lawns light green in winter. Atrazine suppresses Poa annua effectively when applied early in the season.
• Rescuegrass and ryegrass escapes — atrazine has some suppressive activity on winter annual grasses, though control is better on young plants.

Atrazine is labeled for use on dormant Bermuda and is widely regarded as the single most useful post-emergent tool for winter weed management in Texas Bermuda lawns. The prime application window in Arlington is December through February — after Bermuda has been fully dormant for several weeks but before any risk of early green-up in late winter. Liquid atrazine at 1 to 2 quarts per acre (depending on weed pressure and product concentration) applied with adequate water coverage provides 4 to 6 weeks of residual activity.

Metsulfuron (an ALS inhibitor, Group 2) at very low rates is also used on dormant Bermuda for broadleaf and some grassy weed control. It requires careful rate calibration but provides another mode of action for resistance management in programs that rely heavily on atrazine.

What You CANNOT (or Should Not) Spray on Dormant Bermuda

Not every herbicide that would be effective on winter weeds is safe on dormant Bermuda. Several categories of products carry meaningful injury risk even on apparently dormant turf:

• Broadleaf herbicides containing 2,4-D or dicamba: These synthetic auxins can still be absorbed by Bermuda crowns and root tissue even during dormancy, particularly as soil temperatures begin rising in late winter. Applications of 2,4-D + dicamba combinations in January are generally acceptable, but the same products applied in late February or early March — as Bermuda approaches green-up — carry significant injury risk. The emerging Bermuda tissue is far more sensitive to growth-regulator chemistry than fully dormant tissue.
• Anything systemic applied near green-up: The critical danger zone is the transition period in late February through March when Bermuda starts breaking dormancy. As soil temperatures at the 4-inch depth consistently exceed 50°F, Bermuda begins mobilizing stored carbohydrates and activating growth. A systemic herbicide applied during this transition can be absorbed by the newly active tissue and cause widespread injury that takes the lawn weeks or months to recover from.
• Non-selective herbicides (glyphosate): Obviously not safe on Bermuda at any time, including during dormancy. Dormant Bermuda is not dead — glyphosate applied to dormant Bermuda can translocate to the crown and root system and cause severe or total stand loss.

The Timing Risk: When Bermuda Breaks Dormancy in DFW

Bermuda green-up in Arlington typically begins when soil temperatures at the 4-inch depth consistently exceed 50°F for several consecutive days. In a warm year, this can occur as early as late February. In a cooler year it may be mid-March. The unpredictability of late-winter temperature patterns in North Texas is what makes dormant-season herbicide applications a judgment call, not a calendar decision.

A warm week in late February that pushes soil temperatures up can trigger partial green-up — and any systemic broadleaf product applied after that point carries elevated risk. Professional applicators watch soil temperature data and forecast trends carefully. The practical rule is to complete atrazine applications by late February in most years and to avoid any 2,4-D or dicamba applications after mid-February unless soil temperatures confirm continued deep dormancy.

Targeting the Right Weeds at the Right Stage

Winter annual weeds in DFW go through a predictable lifecycle. They germinate in October and November, grow slowly through December and January, and then bolt and mature rapidly in February and March as day length increases. The post-emergent window for dormant-Bermuda applications targets weeds in their small, young stage (December – January) when they are easiest to kill and before they have produced seed. By late February, henbit and chickweed that were not controlled earlier are often large, mature, and more difficult to kill with the same product rates.

This is why the best dormant-Bermuda weed programs treat early — not when weeds become visually dominant in late winter, but proactively in December and January when weeds are small and the Bermuda is safely dormant. Read more about the temperature and stage factors that govern post-emergent effectiveness in our related post on how mode-of-action rotation prevents herbicide resistance in Texas turf for additional context on why product choice matters across seasons.