Purple (or red) Deadnettle is a winter annual often confused with henbit (Lamuim amplexicaule). Both weeds have square stems and belong to the mint family. The leaves of purple deadnettle are triangular in shape and less deeply lobed than henbit. The upper leaves of deadnettle are red to purple in color. The leaves of purple deadnettle have petioles with the petioles of the lower leaves being longer than the upper leaves. The flowers of purple deadnettle are light purple in color. The flowers are arranged in whorls and form in the axis of the upper leaves. Purple deadnettle spreads by seeds. Purple deadnettle is found throughout the United States and Canada.
Purple deadnettle is a winter annual that germinates in the fall or spring. Like henbit, it does best in thin turf. It is usually found in moist fertile soils. It can be found in dormant warm season turf and thin fall seeded cool-season turf. It grows best in the cooler weather of late fall and early spring. Develop a thick stand of turf by proper cultural and fertility practices as well as thinning out problems that are caused by shade will reduce competition from purple deadnettle.
For optimum control, make your post-emergence herbicide application to purple deadnettle that is actively growing and in the seedling to flower stage of growth.