It’s that time again. Each spring Central Kansas gardeners and homeowners notice the small purple flowering weed called henbit which is just beginning to flower now. This common lawn and garden weed often gets people wondering what to do. Is it necessary to use a herbicide to control it or is there more to consider? Learning more about henbit may help.
Henbit is a plant in the mint family, which means like other mints, it has a square stem. This is one of the identification features. The flower is small, pink to purple, lipped, and tubular.
Henbit is classified as a winter annual, which means much of it actually germinated last fall and has been hanging out at about ground level all winter just waiting for spring to arrive. If you go out and look, you can find it at ground level beneath lawn grasses or even on bare soil in gardens in late fall and winter. If you find it on a protected south side of a home it will have already grown large by now. Flowering will often begin in March and flowers are most abundant during the month of April. The plant will grow four to six inches tall as it matures. Once temperatures warm up in June, the plant will have finished its annual life cycle, produced seed, and died off.
Benefits for pollinators
Although henbit is certainly an unwanted invader in many yards and gardens, it does have some benefits that should be considered before deciding to eradicate it completely.
Henbit is such an early bloomer that it is actually an important early spring food source for many pollinators. The small purple flowers of henbit provide both a pollen and nectar source for long tongued bees such as honeybees and bumble bees during the flowering period in March and April.
With this in mind, learning to tolerate henbit can certainly be a help to our local pollinators and is encouraged. Henbit is also quite attractive when a ‘stand’ is in full bloom.
If getting rid of henbit is a must for your situation remember that it should be controlled earlier rather than later. The optimum time to control it in a lawn is in the early fall with a pre-emergent to prevent it from successfully germinating. In Central Kansas, a pre-emergent should be applied in late August or early September (assuming no lawn overseeding is planned) to help stop many winter annual weeds including henbit. Barricade (prodiamine) is a common pre-emergent labeled for henbit that is often used since it has a long soil residual. Other preemergent products labeled for henbit include Dimension (dithiopyr) Gallery (isoxaben), Halts (pendimethalin) and others.
Henbit can also be controlled later in the fall (late October and well into November) after it has germinated with many broadleaf weeds spray products (there are many labeled for henbit). Be sure to follow label direction on any herbicide that is applied. Remember that henbit can continue to sporadically germinate through late fall and even winter and so some later germinating plants may be missed by a herbicide application in October or November.
Spring applied broadleaf weed herbicides can also be effective if applied early enough to stop the flowering and seed production of the plant. Caution is always encouraged, be sure to only spray on a calm day to avoid any unwanted spray drift which can damage other nearby plants that may be breaking dormancy.
Healthy turf is the best weed control
It is important to remember that henbit is rarely a big problem in a healthy lawn that is managed well. Henbit is not very competitive in a dense lawn. A thick and healthy turf is ultimately the best long term weed control in any situation.