I approach lawn care the same way I do analytical problem-solving: by isolating root causes. Henbit tends to thrive in compacted, poorly drained soil, creating a stressful environment where turfgrass can't compete. When the soil is hard and grass growth is weak, it's essentially an open invitation for invasive species like henbit. Just like with test prep strategies, correcting the underlying foundation, in this case, aerating the soil and improving structure, makes all the difference.
You can still kill henbit after it flowers, but results are weaker since the plant is near the end of its life cycle. Henbit has rounded upper leaves on short stems, while purple deadnettle's leaves are more triangular with longer petioles. The most effective active ingredient for homeowners is 2,4-D combined with dicamba or MCPP. Fall pre-emergent works best when soil temperatures drop below ~70degF, typically early fall. Mowing does little to control henbit and can spread seeds if plants have matured. For hand-pulling, remove the entire root when soil is moist. Henbit often signals compacted, thin turf. Dense infestations usually take two full seasons of consistent treatment to clear Albert Richer, Founder, WhatAreTheBest.com