I’ve received a few questions asking what the purple weed is that is appearing in the landscape. It is probably either purple deadnettle (Lamium purpureum) or henbit (Lamium amplexicaule).
These weeds often get confused because they look similar. They both belong to the mint family, have square stems, have an ascending growth habit, opposite leaves, purple/pink flowers, and are winter annuals. When trying to identify if you have purple deadnettle or henbit, key ID traits to tell them apart are listed below.
Key ID traits for purple deadnettle:
- Purple-tinged leaves on upper stem triangular with pointed tips
- Upper leaves with petioles, not directly attached to stem
Key ID traits for henbit:
- Leaves rounded with deep lobes and venation on upper stem
- Upper leaves directly attached to stem with no petioles
- Densely pubescent (hairy) leaves
Since both are winter annual, preventing seed production is key to management. Tillage and herbicides are effective management options for these weeds. Both species are flowering now and management with herbicides will not likely result in full control. Fall or early spring herbicide applications will be most effective at managing problem infestations. Contact your local Iowa State University Extension & Outreach field agronomist for resources regarding control of these weeds.
Another weed that belongs to the mint family and is making lawns appear purple right now is ground ivy (Creeping Charlie, Glechoma hederacea). Unlike henbit and purple deadnettle that are winter annuals, ground ivy is a perennial weed, and also generally stays confined to lawns.