By Kathleen Cue, Nebraska Extension Horticulture Educator
Three weeds we see at this time of year resemble each other so closely that it is often confusing as to which is which. Henbit, ground ivy, and speedwell are flowering right now so are easy to notice. I’ll admit, conversations about weeds are some of people’s least favorite, but talk we must and to this end identification of the weed is a key first step. Why? After all, isn’t a weed a weed and all weeds should be eradicated by any means? Like most things involving plants, it’s just not that simple. Remember that pollinators like these plants for the nectar they provide in early spring. Devoting a small space to these plants is an excellent way to help them out while minimizing square footage overall. So if management is a must, identifying the plant first leads to information about its life cycle, which in turn gives clues about effective ways to manage it.
Henbit, Lamium amplexicaule, is a winter annual and a member of the mint family. The purple flowers begin in March and continue through May. You’ve probably seen this plant numerous times—it is the carpet of purple across fallow fields. It can be distinguished from ground ivy, which also blooms purple, by the leaf attachment. The upper leaves on henbit are sessile, meaning there is no stalk attaching the leaf to the stem. (A way to remember this trait is that the hen squats on the stem!) Henbit spreads primarily by seeds.
Ground ivy (Glechoma hederacea), also a member of the mint family, differs from henbit in that it is a perennial. All leaves of ground ivy will have a stalk (called a petiole) attaching it to the stem. Ground ivy grows very well in urban settings, preferring shaded sites but will also show up in rough areas, such as roadsides. Ground ivy will spread by seed but it is more common to see the plant spreading by root development along stems.
Speedwell, Veronica agrestis, is not in the mint family at all, so the plant won’t have a strong aroma when mowed. Mowing really isn’t a means of management because speedwell really hugs the ground. The flowers of speedwell are tiny, just 1/8 of an inch across and sky blue in color. A winter annual, it shows up in areas of thin turf. Speedwell spreads by seed.
Since henbit and speedwell are winter annuals, a pre-emergence herbicide applied around Labor Day in the fall does an excellent job of keeping weed numbers down. A three-way herbicide (one that has 3 herbicides in one product) and herbicides containing triclopyr provide some post-emergence control for henbit and speedwell. Triclopyr is a good management option for ground ivy with better control achieved when the herbicide is applied in the fall, interfering with the plant’s ability to store food for winter.