What is the Damage of Horsetail to Property, Animals, and Gardens?

December 9, 2025 •

4 min read

Dating back to the prehistoric era, the tenacious horsetail is far more than a simple weed; it is a persistent invasive species with surprising and significant damaging capabilities. The serious damage of horsetail can affect property foundations, agricultural land, and even the health of grazing animals.

Quick Summary

Horsetail is a persistent invasive weed that causes damage through its deep, aggressive rhizomes that can crack hardscaping and block drainage. It is also toxic to livestock, particularly horses, if ingested, leading to vitamin B1 deficiency and neurological problems.

Key Points

Structural Damage: Horsetail's deep rhizomes can push through cracks in concrete, paving, and tarmac, and can block drainage systems.
Livestock Poisoning: Ingesting horsetail, especially dried in hay, is toxic to horses and other livestock due to thiaminase, which causes vitamin B1 deficiency.
Aggressive Invasiveness: Horsetail outcompetes garden plants and crops for resources, stunting their growth and reducing yields significantly.
Difficult Eradication: The plant's ability to regenerate from small root fragments and its resistance to many herbicides make it extremely hard to remove permanently.
Human Health Risks: While often used in supplements, certain horsetail species are toxic, and long-term use can cause thiamine deficiency or adverse interactions with medications.
Spreading Mechanisms: Horsetail spreads via both aggressive underground rhizomes and wind-dispersed spores, making it a threat to large areas.

Understanding the Unique Threat of Horsetail

Horsetail (Equisetum arvense) is a resilient, deep-rooted perennial weed often mistaken for a harmless garden plant. Its ability to spread quickly and colonize new areas is primarily due to its aggressive underground root system, or rhizomes, which can reach depths of up to 2 meters. While native to many parts of the northern hemisphere, this plant becomes a severe problem when it invades human-managed spaces. Its aggressive growth and unique reproductive methods make eradication exceptionally difficult, leading to a host of problems for landowners and farmers.

Structural Damage to Property

Beyond being a garden nuisance, horsetail is a genuine threat to built infrastructure due to its powerful root system. The damage it causes to hard surfaces is well-documented and can lead to costly repairs.

Damage to Paving, Tarmac, and Concrete

Horsetail's deep rhizomes have the strength to push through existing cracks and weaknesses in hard surfaces. This relentless growth causes the cracks to expand over time, leading to significant surface damage.

Paving and Patios: Shoots can emerge between paving stones, lifting them and destroying the integrity of the surface.
Tarmac and Driveways: The plant can exploit small fissures in tarmacadam, pushing through to cause larger, more visible cracks and potholes.
Concrete Foundations: While not as powerful as some larger tree roots, horsetail's rhizomes can aggravate existing damage in foundations and walls by forcing their way into cracks. This compromises structural integrity and increases the risk of water damage over time.

Infiltration of Drainage Systems

Horsetail's invasive rhizomes pose a serious risk to drainage. They can find their way into pipes through loose joints and cracks, where they continue to grow and multiply.

Blockages: Once inside, the roots create dense blockages that obstruct water flow and lead to drainage issues.
Flooding Risk: Compromised drainage can cause water to back up, increasing the likelihood of flooding and water damage to the property.

Impact on Gardens and Agriculture

In gardens and on agricultural land, horsetail's aggressive nature is a major issue for a number of reasons.

Outcompeting Other Plants

Horsetail forms dense clusters of foliage that block sunlight and aggressively compete for water and nutrients.

Reduced Crop Yields: In agricultural fields, horsetail can significantly reduce crop yields by starving them of necessary resources.
Stunted Garden Plants: For gardeners, this means smaller, weaker, and less productive plants. It can easily smother seedlings and smaller, less vigorous plants.

Soil Contamination and Difficult Removal

One of the most problematic aspects of horsetail is how its rhizomes can regenerate from small fragments. Tilling or rotavating a contaminated area can spread the plant rather than destroy it, compounding the problem. This makes traditional removal methods ineffective or even counterproductive, requiring extensive and persistent control measures.

Toxicity to Livestock

For farmers and landowners with grazing animals, horsetail poses a severe health threat, particularly to horses.

Poisonous Compounds: Horsetail contains the enzyme thiaminase, which breaks down thiamine (Vitamin B1) in the animal's body. It also contains toxic alkaloids in certain species, such as Equisetum palustre.
Symptoms of Poisoning: Ingestion can lead to a range of symptoms, including weight loss, uncoordinated movements (staggering), muscle weakness, seizures, and in severe cases, death from exhaustion. The symptoms are more pronounced in horses consuming large quantities, such as through contaminated hay.
Risk in Hay: While grazing animals often avoid fresh horsetail due to its high silica content and unpalatability, the dried plant is palatable and toxic when mixed in with hay.

Potential Risks for Humans

Although field horsetail (Equisetum arvense) is sometimes used in herbal remedies, it is not without risks, especially if the wrong species is used or if taken long-term.

Thiamine Deficiency: Prolonged use can lead to vitamin B1 deficiency due to its thiaminase content.
Interactions with Medication: Horsetail can interact with various medications, including diuretics, lithium, and antidiabetic drugs.
Poisonous Species: Some species, like Equisetum palustre, are highly toxic and should not be consumed by humans.

Comparing Horsetail and Japanese Knotweed Damage


Damage Type	Horsetail (Equisetum arvense)	Japanese Knotweed (Fallopia japonica)
Root System	Deep rhizomes (up to 2m), can regenerate from small fragments.	Powerful rhizomes (up to 3m deep), highly aggressive and regenerative.
Structural Damage	Pushes through cracks in hard surfaces (paving, tarmac) and can infiltrate drains.	Destroys foundations, drainage, and other hard surfaces with brute force.
Toxicity	Toxic to livestock (especially horses) due to thiaminase.	Not toxic, but highly invasive and destructive.
Control Difficulty	Extremely difficult. Requires persistent control over several years; chemical treatment is challenging due to waxy stems.	Extremely difficult and requires professional remediation to avoid legal issues.
Legal Status	Native species, generally not covered by invasive species laws (UK example).	Non-native and subject to strict regulations concerning control and disposal.

Conclusion

The damage of horsetail is far-reaching and extends well beyond the typical nuisance of a garden weed. Its ancient lineage gives it a resilience that makes it incredibly difficult to control, and its invasive nature allows it to compromise hard infrastructure, including patios, driveways, and drainage systems. For rural landowners, the threat of livestock poisoning is a significant concern, requiring careful management of pastures and hay. While humans can consume some forms of horsetail, caution is advised due to health risks and the existence of toxic species. Ultimately, proactive identification and persistent control methods are necessary to mitigate the serious risks this persistent plant poses.

Frequently Asked Questions

Yes, horsetail is poisonous to livestock, including horses, cattle, and sheep, both in its green state and when dried and mixed into hay. It contains thiaminase, which destroys vitamin B1 and can cause neurological disorders.

Yes, while horsetail is not as powerful as some tree roots, its persistent rhizomes can exploit existing cracks in concrete foundations, pavements, and walls. Over time, its growth can expand these fissures and compromise structural integrity.

The safety of horsetail for human consumption varies. While Equisetum arvense is used in some herbal remedies, other species like Equisetum palustre are toxic. Long-term or excessive consumption can lead to vitamin B1 deficiency and other side effects.

Horsetail spreads through two main mechanisms: wind-borne spores and an aggressive, deep-reaching underground root system called rhizomes. It can regenerate from even small fragments of its roots, making manual removal difficult.

Initial symptoms of horsetail poisoning in horses include a scruffy appearance, weight loss, diarrhea, and uncoordinated movements. If untreated, it can progress to severe muscle weakness, staggering gait, and seizures.

Chemical control is challenging due to the plant's waxy cuticle, which resists absorption, and its deep root system. Herbicides often require multiple applications over several years for any significant effect, and brushing the stems before application can increase absorption.

Digging up horsetail can actually worsen the problem because any small root fragments left behind can regenerate into new plants. This is why manual removal is only effective if done meticulously and repeatedly over a long period.