Horsetail is an extremely invasive and deep-rooted weed that can take over a lawn or garden seemingly overnight. To kill horsetail weeds down to the root, you will need to apply weed-killers containing 2,4 D Amine or halosulfuron-methyl. To kill horsetail surface growth, use natural compounds with vinegar, along with a regimen of spore-cutting and hand-pulling to get rid of horsetail.
Keep in mind that horsetail is an extremely tenacious plant, with root networks that extend several feet deep and can spread as far as 20 feet in diameter. As long as there is even a small portion of root in the soil, horsetail can resprout. Killing horsetail is a serious challenge, but it can be accomplished in a few ways.
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Horsetail Weed Identification
Horsetail is a perennial which can be identified by upright shoots with round, needle-like “leaves” growing around the central stalk. It gets its name from its resemblance to a horse’s tail, but has also been compared to a bottle brush. Young horsetail resembles the end of a pine tree branch, although it is a more vibrant green than most pines.
Horsetail is a member of the fern family. Like its cousins, it prefers moist soil and can thrive in low-light, low-oxygen conditions. It typically grows well in acidic soils with high volumes of sand and/or clay.
The Do’s: 6 Ways on How to Kill Horsetail Weeds
Use the Right Chemical Weed-Killer
Roundup and other Glyphosate-based weed killers won’t work on horsetail. However, a top-rated horsetail weed killer has the ability to kill horsetail down to the roots.
- 2,4 D Amine is a compound found in many weed-killing products available at local hardware and garden stores. Many are advertised with “2,4 D” prominently on the label. Lawn care professionals attest to the fact that if used properly, this is one of the few chemicals that can attack horsetail root rhizomes.
- Halosulfuron-methyl is a compound found in sedge and nutgrass control products such as Sedgehammer. It has shown success in attacking horsetail root systems and killing the plant entirely. It may require multiple applications over a 6–12 week period to get results, but it’s a much better option than Roundup.
Use Vinegar as a Natural Weed Killer
Applying a high-strength vinegar, mixed with a small amount of dish soap (to make the vinegar stick to the plants) can kill the above-ground growth of horsetail quickly. The acetic acid in the vinegar attacks horsetail leaves and stems.
While this will not attack root systems like chemical options, vinegar is non-toxic, and can help you wipe out growing horsetail. Repeated applications on new horsetail shoots can continue to weaken the plant, lessening the infestation over time. Beware, vinegar will also harm any other plants it comes in contact with.
To kill horsetail, you should use horticultural vinegar, which contains 15–20% acetic acid (the vinegar at your grocery store only contains 5–7% acetic acid). You can find horticultural vinegar at your local hardware store.
Cut Horsetail Before Applying Weed Killer
Horsetail is notorious for its waxy, tough leaves. This waxy leaf cuticle serves as a natural barrier to toxins of all kinds. It also makes the plant incredibly resistant to both natural and chemical weed killers.
Before applying your weed killer of choice, cut the horsetail with a mower or garden shears. This will allow your vinegar, 2,4-D, or halosulfuron-methyl to enter the horsetail’s system through the wound you’ve made. You will see faster and more effective results by cutting horsetail before applying weed killer.
Improve Soil to Discourage Horsetail
Horsetail thrives in poorly drained areas with acidic soil (typically sandy or clay soils). The following processes will help change soil conditions to make them more suitable for desirable plants and less suitable for horsetail:
- Improve Drainage by filling any boggy or low spots with additional soil. Dig drainage trenches to siphon runoff away from your lawn or garden. Perpetually moist areas are a haven for horsetail and typically a deathbed for the plants or grass you wish to grow.
- Apply Dolomite Lime to the soil. Follow directions for application on the packaging of the dolomite lime you purchase. Lime reduces soil acidity, improving the growth of most plants. Horsetail thrives in acidic environments and doesn’t grow as strongly in less acidic conditions. By changing soil chemistry, you can also make your other plants healthier, thereby choking out horsetail.
- Fertilize 2 weeks after Adding Lime to get the best results. If you apply lime and fertilizer at the same time, the lime and nitrogen will work against one another. Water the lime into the soil, wait at least 14 days and apply a slow-release, high-nitrogen fertilizer to boost desired plant growth and alter conditions against horsetail.
Use Casoron Pre-Emergent Weed Killer
The best way to stop horsetail in its tracks is to kill it while it’s young. In spring, apply Casoron pre-emergent weed killer. An excellent controller of perennials, Casoron is the best pre-emergent for horsetail because it kills sprouts and seedlings that are resistant to most other compounds.
Remember to water after applying Casoron because it needs to be soaked into the soil to be effective against horsetail.
Control any Returning Spores
By using one or more of the previous methods, you will have seriously controlled horsetail growth. You should still remain vigilant during the growing season though. Horsetail is a tough customer. Look out for greenish-brown shoots with a cone at the end—these are horsetail shoots. That cone contains spores that will spread more horsetails!
Keep any resurgent horsetail under control by spraying, cutting, or pulling these new shoots. With a little persistence, your horsetail problems will be a thing of the past.
The Don’ts: Things to Avoid when Killing Horsetail Weeds
Horsetail is a unique weed due to its membership in the fern family and its large root system. Several typical weed-killing tactics won’t work when trying to get rid of horsetail.
DO NOT attempt the following when trying to kill horsetail. These methods will cost you time and money without killing the plant.
- Roundup: Roundup does not kill horsetail weeds. Not only do the waxy leaves of horsetail plants protect it from most topical herbicides, the plant is also very resistant to Glyphosate, the active ingredient in Roundup.
- Sheet Mulching/Ground Covering: Horsetail thrives in the low-oxygen, low-light environment created by covering an area with plastic sheeting or thick mulch. Not only that, but because horsetail establishes such large root networks, it will find uncovered places to sprout. You may hold it back for a season with this method, but sooner or later, horsetail will push up through your mulch, around the edges of it, or even begin to grow underneath your ground covering.
- Hand-Pulling: Don’t expect to get rid of horsetail by hand. Horsetail roots can grow to depths of five feet. You won’t kill the plant simply by pulling the exposed portion. If you follow this method you can expect to battle resurgent horsetail year after year.
Do What Kills Horsetail Weeds for Good
Horsetail is resistant to Roundup, can survive with very little light or oxygen, and has deep roots, so it’s extremely hard to kill. By using a 2,4 D herbicide, or a sedge and nutgrass product such as Sedgehammer, you can eliminate horsetail completely. You can also damage horsetail by using vinegar compounds. With proper drainage, soil management, and fertilization practices you can make your lawn and garden resistant to horsetail.