How to Get Rid of Henbit & Deadnettle

If you have ever watched a hazy purple sheen spread across a dormant lawn or a fallow field in early spring, you have met henbit and its near-twin, purple deadnettle. Both are cool-season annuals in the mint family that germinate in fall, quietly overwinter as small rosettes, then explode into bloom and seed in the first warm weeks of spring before summer heat finishes them off. They exploit thin turf and bare, open soil, and because each plant pumps out a heavy load of seed in a short window, an ignored patch this spring becomes a carpet next year. The reassuring part is that both are shallow-rooted winter annuals with square stems and no spreading root system, so they are far easier to defeat than entrenched perennials — provided you understand that the battle is won in fall, not spring. This guide covers identification, manual and cultural removal, pre-emergent and post-emergent herbicides, product choices, and the timing that breaks the cycle.

How to Identify Henbit and Purple Deadnettle

These two are constantly confused because they grow side by side, bloom at the same time, share square mint-family stems, and both wear purple flowers. The differences are easy once you look closely. Henbit (Lamium amplexicaule) has rounded, scalloped leaves that clasp directly around the square stem with no leaf stalk — the upper leaves wrap the stem like a collar. Its slender, tubular pink-purple flowers rise in whorls from those leaf clusters.

Purple deadnettle (Lamium purpureum) has triangular, heart-shaped leaves on distinct short stalks, and the upper leaves are tinged purple or reddish, giving the whole top of the plant a purple cast even before the flowers open. Its flowers are a similar pink-purple but sit among those colorful upper leaves. A quick field test for both: roll the stem between your fingers and you will feel four flat sides — the square stem confirms a mint-family weed. Crushed foliage of deadnettle has a faint, slightly unpleasant scent.

Both stay low, branching from the base, and rarely exceed 6 to 16 inches. They favor moist, fertile, disturbed ground and thin lawns, and they are among the very first weeds to flower in late winter and early spring — that early purple haze across lawns and crop fields is almost always one of these two. Telling them from the unrelated ground ivy (creeping Charlie) matters too: ground ivy is a creeping perennial that roots at the nodes and persists all season, while henbit and deadnettle are upright annuals that die out in summer heat.

Manual and Cultural Control

Both weeds are a pleasure to pull because the root system is shallow and fibrous with no creeping runners, so plants lift cleanly from moist soil. In beds and small lawn patches, hand-pulling or hoeing is fully effective as long as you act before flowering — once those purple flowers open, seed follows within days. A sharp hoe drawn just under the surface on a dry day severs the seedlings and rosettes and lets them shrivel; this is fast over larger areas of bare or cultivated ground.

Timing is everything with cool-season annuals. The most useful manual work happens in fall and late winter, when the plants are still small overwintering rosettes — clear them then and you prevent the spring seed crop entirely. By the time the lawn is purple in spring, the plants are mature and seeding, so removal is salvage rather than prevention. Do not compost flowering plants in a cool pile; bag or hot-compost them so seed cannot survive.

The cultural cure is coverage and turf density. In beds, maintain 2 to 3 inches of mulch, which denies the light and bare soil these seeds need to germinate. In lawns, a thick, well-fed, properly mowed turf is the best defense — these annuals colonize thin, bare, and shaded patches, so anything that thickens the canopy crowds them out. Mow cool-season grass at 3 inches or higher, fertilize on a sensible schedule, and overseed thin or bare areas in fall so grass fills the space before the weed seed can.

Chemical Control

As with other cool-season weeds, chemical control divides into preventing germination (pre-emergent) and killing existing plants (post-emergent).

Pre-Emergent Herbicides

Because henbit and deadnettle germinate primarily in fall, a pre-emergent applied in late summer to early fall — as soil temperatures cool toward 70°F — is by far the most effective single measure. Isoxaben is excellent against broadleaf winter annuals like these and is labeled for turf and many ornamental beds. Prodiamine and dithiopyr also suppress them and carry over to control crabgrass the following spring. Apply and then water in with about a quarter to half inch of irrigation to activate the barrier in the surface soil. A pre-emergent has no effect on plants that are already up, so it is strictly a prevention step taken before the fall flush.

Post-Emergent Herbicides

1. For henbit or deadnettle already growing in a lawn, use a selective three-way broadleaf herbicide containing 2,4-D, MCPP (mecoprop), and dicamba; both weeds respond well.
2. Treat in fall or late winter while plants are small overwintering rosettes — this is far more effective than spraying mature, flowering spring plants.
3. Spray on a calm day between 50 and 80°F with no rain for 24 hours; these cool-season weeds take herbicide well in mild temperatures.
4. Wet the foliage to just before runoff, and add a surfactant to improve coverage on the small leaves.
5. Avoid spraying new grass seedlings; wait until a freshly seeded lawn has been mowed two or three times before treating.

In bare beds, mulch paths, gravel, or paving cracks where there is no desirable plant to protect, a non-selective glyphosate spray clears these weeds quickly — but it kills everything green, so keep it well off turf and ornamentals. Always read and follow the product label, including listed turf species, crops, and any waiting interval before harvesting edibles.

Recommended Products

For prevention, an isoxaben-based granular pre-emergent is the most targeted choice for these broadleaf winter annuals in beds and turf; a combination prodiamine or dithiopyr granule is the budget pick if you also want spring crabgrass control from the same fall application. For killing existing henbit or deadnettle in turf, any reputable 2,4-D + MCPP + dicamba concentrate or ready-to-spray bottle labeled for broadleaf lawn weeds does the job, applied to small fall or late-winter rosettes. For non-lawn areas, a 41% glyphosate concentrate is the standard spot treatment.

If you garden organically or are clearing a vegetable bed, the synthetics are unnecessary — hand-pulling, hoeing, and mulch are genuinely effective thanks to the shallow roots, and a flame weeder makes short work of seedlings in gravel and pathways. As a bonus, both henbit and purple deadnettle are edible when young (deadnettle is a popular forage green), so untreated plants can go in the salad bowl rather than the bin. Whatever you choose, match the product to the site and never use a turf-only herbicide in a vegetable bed.

Timing: When to Treat by Season

Late summer to early fall is the decisive window. Apply your pre-emergent as soil temperatures cool toward 70°F — typically late August into September across much of the country — to block the main flush of germination before any plants appear. This one well-timed application prevents the bulk of next spring’s purple haze and is the reason experienced lawn keepers rarely fight these weeds in spring.

Fall and late winter are the times to hit any plants that did emerge, while they are small overwintering rosettes and well before flowering. Early spring control is damage limitation — you are killing plants ahead of seed set, but the population is already there. By late spring and summer, the plants flower, seed, and then die back naturally in the heat, so there is little point spraying mature, dying plants. Build your calendar around a fall pre-emergent plus a fall or late-winter cleanup, and the annual cycle breaks.

Preventing Henbit and Deadnettle Long-Term

Both weeds are opportunists of bare, moist, undisturbed soil and thin turf, so the prevention plan is straightforward: never leave soil exposed and never let turf thin out. Mulch beds 2 to 3 inches deep, keep the lawn thick and mowed tall, and overseed thin or shaded areas each fall so grass — not winter annuals — claims the open ground. Relieve compaction with core aeration and improve drainage in damp spots, since these conditions favor the weeds.

Then break the seed bank by removing plants before they flower every time, and within two or three seasons the spring purple flush fades to nothing. For broader lawn-density tactics that crowd out cool-season weeds, see the related guides in our Outdoor Living section. If these weeds are creeping into vegetable beds, our Urban Gardening guides cover mulching and raised-bed soil management that keep beds weed-resistant, and you can compare spreaders, sprayers, and hoes in our Tools & Gear reviews.