Horsetail or mare’s tail (Equisetum arvense) 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.
What is horsetail?
Horsetail is an invasive, deep-rooted weed with fast-growing rhizomes (underground stems) that quickly send up dense stands of foliage.
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 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.
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.
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.
Weedkillers for gardeners (Adobe Acrobat pdf document outlining weedkillers available to gardeners; see sections 4 and 5)
Chemicals: using a sprayer
Chemicals: using safely and effectively
Chemicals: using spot and broad-scale weedkillers
Common name Horsetail, mare’s tail
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.