Keeping Weeds Out of Crepe Myrtle Tree Rings in North Texas All Season Long

The tree ring around a crepe myrtle is one of the most visible parts of a North Texas front yard, and it’s also one of the most reliably weedy. Whether you’re dealing with bermudagrass creeping in from the lawn, spurge mats forming between the mulch, or bermuda suckers pushing up from the tree’s own root system, keeping a crepe myrtle ring clean requires a layered approach tied to the right timing. This is the full picture of what actually works in the DFW climate for year-round flower-bed weed control around one of North Texas’s most popular trees.

Why Crepe Myrtle Rings Are Especially Prone to Weeds

Tree rings around crepe myrtles share several characteristics that drive chronic weed pressure. First, the rings are typically mulched but shallow — many homeowners apply only one to two inches of mulch, which is not enough to suppress the DFW weed seed bank. Second, the canopy of a crepe myrtle, especially a standard (tree-form) variety, is high enough that substantial light reaches the ground beneath it for most of the day. Third, crepe myrtles are frequently irrigated, especially in the summer blooming months, and that irrigation keeps the soil in the ring consistently moist.

The combination of light, moisture, and shallow mulch creates conditions where annual grasses and broadleaf weeds can get established with almost no resistance. Bermudagrass runners from adjacent lawn panels are the most aggressive invader — they find the boundary between lawn and ring and push through any thin spot in the mulch edge continuously from April through October.

Sucker Growth: The Weed-Like Growth That Is Actually Part of the Tree

Many homeowners mistake crepe myrtle suckers — shoots growing from the base of the trunk or from roots near the surface — for weeds. They are technically part of the tree, but they behave like a weed problem in the ring: they emerge persistently, grow vigorously, and require repeated removal. The most effective approach is to snap them off as close to their origin as possible rather than cutting with pruners, which stimulates more sucker production. Sucker production is heaviest on stressed trees and those with shallow surface roots exposed by thin mulch. Maintaining proper mulch depth reduces sucker emergence significantly.

Pre-Emergent Application in Crepe Myrtle Rings

A properly timed pre-emergent application is the most efficient tool for keeping crepe myrtle rings clean through the growing season. Crepe myrtles are tolerant of the common ornamental pre-emergent active ingredients, including prodiamine, pendimethalin, and isoxaben, when applied at labeled rates to established trees.

• Late January through early March: First application targeting summer annual seeds (crabgrass, spurge, annual grasses). Apply to the full ring surface after any mulch refresh so the chemical contacts soil through the mulch layer when watered in.
• Early September: Second application targeting cool-season annuals (annual bluegrass, henbit, chickweed) that flush hard through October and November in DFW tree rings.
• Water in within 24 hours: Pre-emergent granulars need rainfall or irrigation to activate. An inch of water moves them into the top inch of soil where the germination zone is. Without water-in, the product just sits on top of the mulch and degrades in UV light.

Stopping Bermudagrass Encroachment at the Ring Edge

The hardest long-term weed challenge in crepe myrtle rings is bermudagrass. No pre-emergent stops established bermudagrass runners coming in from the lawn — pre-emergents only prevent seed germination. Runners are vegetative growth, not seedlings. Stopping bermuda at the ring edge requires a physical or chemical barrier at the boundary.

• Deep edging: A vertical cut with a half-moon edger or spade along the ring boundary, repeated monthly through the growing season, severs runners before they root into the ring. This is labor-intensive but highly effective when done consistently.
• Plastic or metal ring edging: Buried steel or aluminum edging with at least five inches of vertical depth slows bermuda runner spread. Bermuda will eventually bridge over or find gaps, but it significantly reduces the frequency of invasion.
• Selective grass herbicide: Clethodim applied directly to bermudagrass that has entered the ring kills it without harming the crepe myrtle above. Requires multiple applications spaced two to three weeks apart for full suppression of established rhizomes.

Mulch Depth and Type for Crepe Myrtle Rings

Three to four inches of coarse cedar or hardwood mulch is the right target for a crepe myrtle ring. Coarser material decomposes slower than fine-shredded bark and maintains effective light blocking longer. Keep mulch pulled back from direct contact with the trunk — two to three inches of clearance at the base prevents bark moisture retention and the fungal issues that follow. Extend the ring as far as possible from the trunk: ideally matching or slightly exceeding the drip line of the canopy. A wider ring with proper mulch is far more effective and lower maintenance than a tight ring with inadequate coverage.

For a deeper look at how mulch placement in ornamental areas affects weed outcomes and plant health, see our analysis of weed problems around Knockout roses in North Texas.

Year-Round Maintenance Calendar for Crepe Myrtle Rings in DFW

• January–February: Prune any needed crepe myrtle shaping. Apply pre-emergent. Top up mulch to three to four inches.
• March–May: Monitor for spurge and annual grass emergence; spot-treat with post-emergent as needed. Edge bermuda runners monthly.
• June–August: Spot-treat any escaped bermudagrass with clethodim. Remove suckers by hand. Recheck mulch depth after heavy summer rains that compact and scatter it.
• September: Apply second pre-emergent application. Refresh mulch if depth has fallen below two inches.
• October–December: Pull any cool-season weeds that escape pre-emergent coverage. No additional chemical applications needed through winter dormancy.