Henbit: identify it, treat it, keep it out
Henbit is a winter annual in the mint family: it germinates in fall, overwinters as a small rosette, then paints thin lawns purple in early spring before setting seed and dying by summer. If your lawn blooms purple every March, the fix happens the previous September.
How to identify henbit
- Purple-pink tubular flowers in whorls near the stem tops in early spring
- Square stems (roll one, you will feel four corners), typical of mints
- Rounded, scalloped leaves that clasp directly around the upper stem
- Upright growth to about a foot, unlike its ground-hugging relative creeping Charlie
Don't confuse it: Purple deadnettle blooms alongside henbit and looks similar; its upper leaves are triangular, stalked, and often purple-tinged rather than clasping.
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When to treat
Prevention (pre-emergent)
Apply before germination, when soil reaches about 65°F.
Window: Early to mid fall
Typical dates: Before soil drops below 65°F in fall (winter annual germinates in fall)
Treatment (post-emergent)
Best time: Late fall or early spring before flowering
Target stage: Actively growing rosette stage
Conditions: Apply when weeds are dry · No rain for 24 hours · Temps 45-65°F
Germination starts around 40°F soil temperature (optimal 50°F). Track your ZIP's live soil temperature or get an exact plan from the herbicide timing calculator.
Control plan
- 1Apply fall pre-emergent before soil drops below 65°F
- 2Post-emergent with 2,4-D or triclopyr in fall or early spring
- 3Improve lawn density to prevent fall germination
- 4Plants die naturally in late spring but will have already set seed
Good to know
- • Winter annual broadleaf with purple flowers in early spring
- • Square stems and scalloped leaves in opposite pairs
- • Germinates in fall, flowers and dies in late spring
- • Often appears in thin or newly seeded lawns
Products that work on henbit
These picks are not filtered to your lawn. Some herbicides damage certain grasses (atrazine is for warm-season lawns; Trimec harms St. Augustine). Verify your grass type on the product label before applying, or use the herbicide timing calculator for grass-filtered recommendations. As an Amazon Associate we earn from qualifying purchases.
post-emergent
Hi-Yield 2,4-D Selective Weed Killer
2,4-D · Spring or fall when weeds are actively growing
Safe for: Kentucky Bluegrass, Tall Fescue, Fine Fescue, Perennial Ryegrass and more
Hi-Yield 2,4-D Selective Weed Killer on Amazonpost-emergent
Trimec Classic
2,4-D, MCPP, Dicamba · Spring or fall when weeds are actively growing
Safe for: Kentucky Bluegrass, Tall Fescue, Fine Fescue, Perennial Ryegrass and more
Trimec Classic on Amazonpost-emergent
SpeedZone Broadleaf Herbicide
2,4-D, MCPP, Dicamba, Carfentrazone · Spring or fall when weeds are actively growing
Safe for: Kentucky Bluegrass, Tall Fescue, Fine Fescue, Perennial Ryegrass and more
SpeedZone Broadleaf Herbicide on AmazonWhere it's most common
Frequently asked questions
When do I prevent henbit?
Early fall, with a pre-emergent as soil temperatures fall through the low 70s, the same window as Poa annua prevention. By the time you see purple flowers in spring, the plant is finishing its life cycle and prevention is a year late.
Should I bother spraying henbit in spring?
Usually not. Spring henbit is weeks from dying naturally, and mature plants resist herbicide anyway. Mow to limit seed set, then put the effort into fall prevention and thickening the lawn.
Why does henbit love my garden bed edges?
Disturbed, bare fall soil is its ideal seedbed. Mulch beds before fall germination and keep lawn edges dense going into autumn.
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