Henbit (Lamium amplexicaule) is a common winter annual weed that quickly colonizes lawns and garden beds during the cooler months, often becoming noticeable when it bursts into bloom in early spring. This aggressive plant forms dense mats across turfgrass. Effective removal depends on correctly identifying the plant and choosing the right combination of manual and chemical controls. Understanding its life cycle is the first step toward successful eradication.
Confirming the Target: Identifying Henbit
Henbit is a member of the mint family, distinguished by its square-shaped stem. The stems are typically green but often display a purplish hue as they mature and grow up to a foot tall. The leaves are opposite, rounded or heart-shaped with scalloped edges, and the upper leaves appear to clasp the stem without a stalk.
Its flowers are small, tubular, and pinkish-purple, often clustered in whorls near the top of the plant. Henbit is frequently mistaken for purple deadnettle, a close relative, but true Henbit’s upper leaves are sessile, or stalkless, which helps distinguish it. As a winter annual, it germinates in the fall, grows in winter, and dies off in the heat of summer, which dictates proper treatment timing.
Manual and Cultural Methods for Removal
For small infestations or in areas where chemical use is a concern, manual removal is a viable option. This method is most effective when the weed is still young and has not yet started to set seeds. The shallow, fibrous root system makes it relatively easy to pull, especially when the soil is moist.
When hand-pulling, grasp the plant firmly at the base and gently pull upward to ensure the entire root structure is removed. Leaving the root behind can allow the plant to regrow. In garden beds, a three-inch layer of organic mulch can be applied to physically block the Henbit seeds from sprouting.
Cultural methods focus on making the environment unfavorable for this weed, which thrives in thin or overly moist areas. Mowing the lawn at the proper height encourages a dense, healthy canopy that crowds out the Henbit seedlings. Improving soil drainage, perhaps through aeration or adding organic material, will reduce the overly moist conditions it prefers.
Effective Herbicides and Application Strategy
Chemical control offers the fastest and most comprehensive method for killing Henbit, relying on two strategies: pre-emergent and post-emergent herbicides. Pre-emergent herbicides are the most effective long-term solution because they prevent the weed from sprouting. These products create a chemical barrier in the soil that inhibits seed germination.
The optimal time for pre-emergent application is in the early fall, typically when soil temperatures drop to approximately 70 degrees Fahrenheit. This timing intercepts the Henbit seeds as they begin to germinate. Common active ingredients found in effective pre-emergent products include Prodiamine and Dithiopyr.
Post-emergent herbicides are used to kill Henbit plants that are already actively growing. Since Henbit is a broadleaf weed, selective broadleaf herbicides are the correct choice, as they target the weed without harming the surrounding turfgrass. Look for products containing a combination of active ingredients such as 2,4-D, dicamba, and MCPP, often referred to as a three-way mix.
Application success is highest when the Henbit plants are small and young, before they begin flowering and seeding in the spring. Once the weed has heavily flowered, the herbicide is less effective, and the plant has already dropped seeds for the next season. Always apply these chemicals according to label instructions, avoiding application during periods of high heat.
Long-Term Prevention and Lawn Health
The most durable defense against future Henbit infestations involves cultivating a dense, healthy lawn that leaves no room for the weed to establish itself. Henbit seeds require bare or thin spots in the turf to germinate successfully, so a thick, vigorous stand of grass acts as a natural barrier. Overseeding with favorable turfgrasses in the fall is a proactive step that fills in sparse areas and increases turf density.
Proper lawn care practices, including deep and infrequent watering, encourage the grass to develop a strong, deep root system that can outcompete weeds for resources. A consistent fertilization program also contributes to overall turf health, giving the grass the nutrients it needs to grow thickly and robustly. Because Henbit is a winter annual that germinates in the autumn, focusing on good lawn health and pre-emergent treatments during the fall season is the most important factor for long-term prevention.