Each spring Central Kansas gardeners and homeowners notice the small purple flowering weed called henbit which is 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.
Biology
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 see it at ground level beneath lawn grasses or even on bare soil or 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 the plant will grow four to six inches tall as it matures. Once temperatures warm up in June, the plant will have finished its life cycle 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 will provide nectar and pollen for both bumblebees and honeybees. With this in mind, learning to tolerate henbit can certainly be a help to our local pollinators and is encouraged.
Control
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 fall with a pre-emergent to keep it from germinating. A pre-emergent can be applied in mid-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.
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 it). Be sure to follow label direction on any spray that is applied.
Spring applied broadleaf herbicides are also 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.
It is important to remember that henbit is rarely a big problem in a healthy lawn that is managed well. A thick and healthy turf is the best weed control for the long term.
Central Kansas Lawn & Garden Blog 