Field Horsetail

Field horsetail is a common weed that can be difficult to distinguish from other plants. It resembles grasses and rushes, with tall stems and long leaves. The plant thrives in moist conditions, which are often found near lakes or streams.

Field horsetails are one of the most common weeds in lawns and gardens because they grow rapidly even when not watered by humans.

This blog post will provide an in-depth guide on what Field Horsetail are, how they grow, and how to eradicate them from your garden.

Quick Facts

Common names: bottle-brush, horse pipes, mares tail, common horsetail, horsetail, scouring rush
Scientific name:
Equisetum arvense
Family:
Equisetaceae
Origin:
non-native
Flowering season:
March to October
Habitat:
grassland, wasteland, streams, rivers, beds, borders, lawns, paths and patios

Field Horsetail Identification

It can be identified by its long, thin stems with small clusters of leaves at the top and brownish-green spore cases (bases) on the stem.

Horsetail is a perennial weed that grows in moist areas such as near rivers or streams or in wet soil.

What does Field Horsetail look like?

Characteristics that make up the Field Horsetail leaf, stem, root and flower are detailed below.

The plant spreads among cultivated plants, making for a messy appearance and competing for water and nutrients.

Hollow horsetail plant stem with radial leaves
Hollow horsetail plant stem with radial leaves

Leaves: The whorls of leaves develop up the stem and resemble the appearance of a Christmas tree.

The leaves sprouting off the stems in a radial pattern
The leaves sprouting off the stems in a radial pattern

Stems: It has slender green stems with dark brown joints. The stems are hollow with nodes on them called joints and have small hairs running along their lengths.

Both stems and branches have teeth around each node.

Roots: The root system (rhizomes) can be extensive both horizontally and vertically and may reach over 1.5 m deep depending on substrate and water table. Over half the rhizomes are found in the upper 25 cm of soil.

The roots cannot tolerate dry conditions either.

Flowers: Field horsetail produces small white flowers with six petals that form long drooping clusters along the stem at intervals of about one foot from ground level and above.

Spores: The plant reproduces by spores that are readily wind-dispersed.

The cone-bearing fertile stems develop from subterranean buds formed the previous summer and persist for about 10 days after emergence.

A single cone on each fertile stem can release up to 100,000 spores that germinate quickly on moist surfaces.

The white spore sacs hanging down are sometimes known as ‘teeth’ and for a good reason from looking at them.

The Problem

The plant has creeping rhizomes which can go down as deep as 7m which makes them extremely difficult to remove, especially if they are invading a border. They are known for entering gardens by spreading underground from neighbouring land or properties.

Horsetail / Marestail is fast becoming the biggest problem weed in the UK growing through driveways & paths, as well as covering industrial sites.

Field Horsetail Seasonal Changes

Being a relative of ferns, common horsetail does not reproduce via pollen but via spores which are borne on the plant’s reproductive stems.

Cone shaped head of the Field Horsetail opening up in Spring
Cone-shaped head of the Field Horsetail opening up in Spring

Field Horsetail in Spring

The plant produces light-brown stems (20-50 cm) in late spring, topped with cone-like structures, and these are followed by light-green shoots which can be up to 60cm in height.

Field horsetail is a rhizomatous perennial with fertile non-photosynthetic spore-producing stems in March-April and green vegetative stems in late spring.

Field Horsetail in Summer

In summer, sterile green shoots develop into fir tree-like plants, 60cm (2ft) tall.

Maximum growth is achieved in July with the rhizomes grow rapidly from June to July and continue to elongate beyond October.

Field Horsetail in Autumn

It’s tall (5-60cm height) light green, fir tree-like shoots are easily recognised throughout the summer and fall (pointed green shoots with folded needle-like leaves pointing upward around the stem).

Field Horsetail in Winter

The plant dies back completely each winter, so it’s easy to spot because it turns brown when dry rather than green like most other plants do.

Growing only a few feet off the ground it can cover a large area and become the dominate plant
Growing only a few feet off the ground it can cover a large area and become the dominant plant

How to get rid of Field Horsetail

It grows quickly and spreads easily, making it difficult to remove without the use of herbicides or other chemicals.

The best way to control horsetail weeds in your lawn or garden is to remove them completely from the soil surface as well as below the ground where they are growing. Below we list the best methods to achieve this.

Method One – Herbicide Treatment

The best way to get rid of field horsetail is by using a herbicide that contains glyphosate in autumn after the leaves have died back.

Spray shoots with weedkiller in summer. Tread down the shoots before spraying to bruise and crush them, which will allow the herbicide to enter the plant and be taken down to the roots. This method proves to be the most effective way of dealing with this weed.

Applying the weed killer anytime up until late summer is advisable.

Horsetail is persistent and several applications over a number of years will be required.

Method Two – Digging it out

Although rhizomes at the surface can be forked out, deeper roots will necessitate a significant amount of digging. Shallow, infrequent weeding is ineffective and can exacerbate the situation by allowing the plant to regenerate from any small fragments left behind.

If done over a long period of time, eliminating shoots as soon as they appear above ground might lessen infection.

You will need to wear gardening gloves when doing this so you do not get any sap on your skin or irritate it if you have an allergy.

Always be sure to clean tools thoroughly after each use since this weed spreads via spores that remain on surfaces even when blades have been sheathed during transport from one location to another.

Clumps of Field horsetail growing wildly in summer
Clumps of Field horsetail growing wildly in summer

Management of Field Horsetail

Remove rhizomes by digging as deeply as possible. The deep roots of established horsetail colonies will re-grow. Regularly removing the shoots and rhizomes as soon as they appear will weaken the plants, but total eradication requires determination over a number of years.

Where horsetail is growing in grass, regular close mowing will cause it to die off, although it may persist in borders at the edge of lawns.

Because new stems develop from rhizome fragments and tubers, horsetail is difficult to manage through cultivation.

The growing vegetative stems can penetrate some woven polypropylene mulches, however, black plastic sheeting has been proven to destroy or suppress rhizomes in the upper layers of soil.

Horsetail can withstand flooding and fire, although it is susceptible to water stress in droughts, especially when competing with other plants.

The plant can be dug out but deeper roots will need excavating, and even the smallest piece left behind will likely re-grow into a new plant. There are very few chemicals that will control this weed and glyphosate alone will do little to stop it.

In Conclusion

Field horsetail is an invasive weed that grows in large clumps. It’s important to identify and remove this pest from your property because it can spread quickly, preventing other plants from growing in the area.

Removing this weed from your property will allow other plants and grasses to thrive, adding beauty to your home.


How does Horsetail / Marestail spread?

It spreads via its root system called rhizomes and from stem fragments in composts or manures. It can also regrow from spores.