It’s springtime and as folks gear up to work in the garden, flower beds and yard, there’s a good chance you’ll see henbit and its lookalike, purple deadnettle, along with smelling and observing the grass-like perennials wild garlic or wild onion.
Wild garlic (Allium vineale) and wild onion (Allium canadense) are two common perennial weeds that are often confused with one another as both look like grasses and both have an onion smell when crushed.
The best way to tell the difference is to look at the leaves. Wild onions have flat, solid leaves while garlic has hollow, round leaves. Both plants emerge in the fall from underground bulbs and grow through the winter and spring. In late spring, greenish pink to purplish flowers are borne in clusters at the stem tip. In early summer, plants die back while the underground bulbs persist in the soil for several years.
For controlling these two lookalikes, pulling up the weeds is an option; however, it’s likely bulblets will be left in the ground and new leaves will later re-emerge to make even more plants.
For best results, dig them out with a trowel if they haven’t already taken over your lawn. For larger areas, three-way broadleaf herbicides containing 2,4-D, dicamba and mecoprop (MCPP) will provide control of wild garlic and wild onion with repeat applications.
Look for these active ingredients in granular products in your area. Apply in November, very early spring, and again the following November for best control. Do not apply these herbicides during lawn green-up, over the root zone of nearby trees and shrubs, nor to newly seeded grasses until well established (after the third mowing). Treated areas may be reseeded three to four weeks after application.
Purple deadnettle and henbit are both purple flowering winter annuals that have square stems and are members of the Lamiaceae (mint) family. Both are fairly short-lived with early spring blooms followed by death as the temperatures rise in late spring and early summer. Seeds will germinate in the fall or winter for another round of growth as warm temperatures fluctuate throughout winter and early spring.
Purple deadnettle is sometimes referred to as bee nettle because it provides an early source of nectar for some bees. While this weed can be unwanted by some, others enjoy it as an edible potherb added to salads and soups, or made into medicinal tea. Deadnettle leaves are paired opposites that are somewhat heart-shaped or triangular with serrated edges, and are crowded along the top portion of the stem. They tend to be purple or reddish and are attached to the stem with petioles. Flowers are usually pink.
Henbit leaves are paired opposites as well, yet they are rounder, more gently scalloped at the edges, greener, and attached directly to the stem without petioles. Henbit flowers are usually blue or purple.
Both plants tend to grow in thin lawns, unplanted fields and along roadsides, especially where moisture remains available.
The best way to avoid these two look-a-likes in the lawn and garden is to maintain a healthy soil with a thick full stand of our cool season grasses. This is accomplished by mowing at proper heights, using appropriate rates of fertilizer at the right time of year and maintaining proper moisture levels in the soil. If necessary, purple deadnettle can be controlled with a post-emergent application of a broadleaf herbicide in the springtime. Henbit is more difficult to control requiring fall applications of two or three-way broadleaf herbicides such as 2,4-D, MCPP and dicamba. Be sure to read the label for more detailed instructions. For more information on weeds in the turf go the NCSU link: www.turffiles.ncsu.edu/weeds-in-turf.
Christine Bredenkamp is NCSU horticulture extension agent for Jackson and Swain counties.