For those looking to learn about how to get rid of henbit, chances are, it’s becoming a nuisance in your garden, affecting the growth of other plants, or it’s ruining your lawn. Those things it will do, despite it being defined as both a beneficial plant AND an edible plant belonging to the mint family.
For gardeners with gorgeous flowerbeds and immaculately maintained lawns, the flowering henbit – as gorgeous as it may look with it’s cute purple flowerheads – is a weed and a seriously invasive one that needs to be brought under control.
The nutrients it consumes from the soil can put your other plants in a choke-hold, starving them of essential nutrients they need to thrive. Unless you have a wildlife garden and need to keep this type of plant around, it’s best to know how to get rid of henbit or at least suppress root establishment as a longer-term control method that doesn’t kill your plants and lawn in the process of trying to control the weed population in your yard.
Clearing Up the Difference Between Henbit and the Purple Deadnettle
Despite being eerily similar species of plants, and both being heavy garden invaders, both of these plants need to be controlled, whether you have acres of land, or a small patch of your garden being overtaken with purple deadnettles or henbit weeds.
The scientific term for these plants is different and the name difference reflects how you can tell the difference.
- A henbit plant is called Lamium Amplexicaule
- A purple deadnettle is called Lamium Purpureum
Note the word amplexicaule. In botany terms, that refers to how leaves attach to the stem of the plant. An amplexicaule plant attaches directly to the stem without a petiole.
Henbit flowers can have leaves attached to petioles but never on the upper leaves. The higher leaves on the stem surround it without attaching to a petiole.
Another thing to look at is the shape of the leaves. The leaves on a henbit are circular with serrated edges, whereas the leaves on a purple deadnettle are pointed at the tips of the leaves.
The stems on both are tubular rather than cylindrical, which is something that differentiates these pollinating weeds from other types.
In most gardens, it’s the thinner parts of a lawn that they first take root. This is because thinner lawns allow more water to penetrate into the soil providing the moist environment henbit seeds need to germinate.
How to Get Rid of Henbit on Lawns Without Killing Your Grass
The henbit flower prefers any soil that’s moist and has shade. Most garden lawns have this type of environment, in particular those using an automated sprinkler to keep the grass watered. The majority of warm-season turfgrasses only need an inch of rain per week to maintain a lush lawn.
Anything above that can make it a beneficial breeding ground for weeds to germinate and take over as ground cover. You’ll also find these growing under shrubs and in flower beds due to the partial shade and existing moisture.
When you spot a henbit near your plants, they should be removed by the root and the soil should be treated to prevent henbit seeds from taking root.
An efficient method of treating existing flowerbeds and small patches of lawn showing an early presence of henbits starting to grow is to use corn gluten meal to prevent the weed from rooting.
Applying Corn Gluten Meal as a Pre-Emergent Henbit Treatment
As far as organic pre-emergent treatments go, corn gluten meal is top of the most popular, mostly because, it’s a tricky procedure that needs to be done with impeccable timing, careful application and repeated treatments. It’s not a once-and-done process, but, nevertheless, for the organic gardener, it’s a super way to control henbit, while also adding a slow-feed nitrogen boost to your soil. That’s right, corn gluten meal can be used as both a pre-emergent for herb control and part fertilizer for your beneficial plants.
Corn gluten meal is a by-product from corn milling and it is powdery so it doesn’t have the thickness needed for a mulch treatment. What it does have is 10% nitrogen in the powder and when applied to soil, it slowly releases over the course of a few months.
This is only effective when applied as a pre-emergent, meaning before the seeds germinated. It won’t stop seeds from germinating, however, what it does do and very effectively is inhibits root growth. When applied correctly, henbit seeds can still germinate shoots but they cannot establish roots. Without roots, they will die.
The tricky part to using corn gluten meal to get rid of henbit is moisture control. Too much water will help the henbit to establish a root, in which case, it will return. There is absolutely no point in using this as a post-emergent because in contrast to what you’re trying to do, it will take the opposite effect and act as a fertilizer encouraging weed growth.
Getting rid of henbit weeds with corn gluten meal requires precise timing as it needs about 1/4 of an inch of water added right after application, followed by up to two days of completely dry conditions. The dry spell is the most important as if the soil gets moisture within two days of watering in, it can provide just enough nutrients for henbit to establish a root, which is all one needs to re-emerge.
For best results, problem areas of your lawn or flowerbeds should be treated once monthly, or at the longest, every six weeks because a single application will only suppress around 60% of the henbit seeds.
In reality, there’s no such thing as an effective one-pass weed suppressant. Every treatment requires repeat application and it’s the same when you’re using corn gluten meal.
In practice, for small patches on your lawn or in a flower bed, the best use of corn gluten meal is to apply it in the spring and again in the fall season. As mentioned, around 60% of seed germination can be suppressed per application.
Continued treatments twice annually should see no weed roots in the treated area within two to three years of using this. It is a long-term management process to eliminate weeds, but then again, nothing is effective at supressing weeds 100% on a single-pass treatment.
It should also be noted that if you do choose to use corn gluten meal, it has the same effect of root inhibition on any seed so if you plan to grow any plant from seed, or apply lawn seed to thicken your lawn, the corn gluten meal will inhibit the growth of those too.
Corn Gluten Meal applications are ideal for organic gardening, in particular if you have henbit weeds establishing around food crops such as strawberries or a vegetable patch where chemical herbicides are not suited. For turfgrass patches, herbicides may be effective.
Using Herbicides to Kill Henbit Weeds
If you need to use herbicides, you still need to time the application because as henbits are winter annuals, these need to be treated before and after summer due to how this cold-season annual grows. The same applies to other winter annuals that can’t tolerate high temperatures.
Applying a pre-emergent herbicide is ideally done in September, just as the temperatures are dropping, which is when cool-season annuals start to germinate. When these flower, they’re actively spreading seeds around the area, which is why they’re highly invasive. Once they flower, the seeds will surround each weed and it’s those that you need to prevent from forming roots when the seeds start to shoot.
Pre-emergent herbicides are one way to do that, but depending on where you’re applying it, you may need a selective herbicide, meaning you can apply to a turfgrass and it will selectively target the weed without affecting the grass.
Products labelled as 2,4-D are among the most common selective herbicide, however, for smaller areas, spot-treating with glyphosate can help get rid of henbit. But unlike 2,4-D, glyphosate is not selective and will inhibit the growth of any plant it comes into contact with.
Like any garden weed though, the most effective strategy is to do the back-breaking work of hand-pulling every henbit, purple deadnettle or any other unwanted plant you have in your garden or flower bed out by hand. Even pulling them out manually though, won’t stop seeds already spread from germinating so once you’ve pulled out the weeds, you’ll need to keep doing that until all the seeds have germinated, established growth and then been picked off.
To learn more about weed control, check out my article about removing weeds from a large area.