Horsetail

Horsetail (Equisetum arvense), often called mare’s tail, is an invasive, deep-rooted perennial weed that will spread quickly to form a dense carpet of foliage, crowding out less vigorous plants in beds and borders.

Horsetail

Quick facts

Common name Horsetail, mare’s tail (misapplied)
Botanical name Equisetum arvense
Areas affected Beds, borders, lawns, paths and patios
Main causes May establish from seed, but usually arrives via rhizomes from neighbouring gardens, or stem fragments in composts or manures
Timing Seen in spring and summer; treat in late summer.

What is horsetail?

Horsetail is an invasive, deep-rooted weed with fast-growing rhizomes (underground stems) that quickly send up dense stands of foliage. 

Appearance

Horsetail is easily recognised by its upright, fir tree-like shoots that appear in summer.

In spring, fertile light brown stems, 20-50cm (10-20in) tall, appear with a cone-like spore producing structure at the end of the stems.

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

The problem

The creeping rhizomes of this pernicious plant may go down as deep as 2m (7ft) below the surface, making them hard to remove by digging out, especially if they invade a border. They often enter gardens by spreading underground from neighbouring properties or land.

Control

Non-chemical controls

Removing horsetail by hand is difficult. Although rhizomes growing near the surface can be forked out, deeper roots will require a lot of excavation. Shallow, occasional weeding is not effective and can make the problem worse, as the plant can regrow from any small pieces left behind. However, removing shoots as soon as they appear above the ground can reduce infestation if carried out over a number of years.

If horsetail appears in lawns, it can be kept in check by mowing regularly.

Chemical controls

Infestations of horsetail can be weakened with weedkiller.

  • On vacant soil, where there are no herbaceous perennials, bulbs or crops, you can use Bayer Ground Clear Weedkiller containing glyphosate/flufenacet/metosulam to inhibit new shoots
  • Tough weedkillers containing glyphosate (e.g. Scotts Roundup Ultra 3000, Scotts Tumbleweed, Bayer Tough Rootkill, Bayer Garden Super Strength Weedkiller or Doff Maxi Strength Glyphosate Weedkiller or for spot treatment use Scotts Roundup Gel) can be applied in late summer when growth is strong. Before using, bruise the shoots with a rake to ensure effective penetration

Remember: horsetail is persistent, and several applications – possibly over a number of years – may be necessary to completely eradicate the problem.

Download

Weedkillers for gardeners (Adobe Acrobat pdf document outlining weedkillers available to gardeners; see sections 4 and 5)

Links

Chemicals: using a sprayer
Chemicals: using safely and effectively
Chemicals: using spot and broad-scale weedkillers

Advertise here

Video exclusive for RHS members: expert advice on dealing with slugs and snails

Sign into the RHS website to watch video Sign in

Sign in

Did you find the advice you needed?

RHS members can get exclusive individual advice from the RHS Gardening Advice team.

Join the RHS now

Discuss this

for the site or to share your experiences on this topic and seek advice from our community of gardeners.