What is horsetail?

Horsetail is an invasive, deep-rooted weed with fast-growing rhizomes (underground stems) that quickly send up dense stands of foliage. This page looks at options for gardeners when horsetail is becoming a problem. 

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

The RHS believes that avoiding pests, diseases and weeds by good practice in cultivation methods, cultivar selection, garden hygiene and encouraging or introducing natural enemies, should be the first line of control. If chemical controls are used, they should be used only in a minimal and highly targeted manner. 

Cultural control

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.

Weedkiller control

Infestations of horsetail can be weakened with weedkiller.

• On vacant soil, where there are no herbaceous perennials, bulbs or crops, you can use SBM Job Done Path Weedkiller (ready to use only) and Weedol Pathclear products containing glyphosate/diflufenican to inhibit new shoots
• Tough weedkillers containing glyphosate (e.g. Roundup Tree Stump & Rootkiller, SBM Job Done Tough Weedkiller (soluble sachets only), Doff Weedout Extra Tough Weedkiller or Westland Resolva Pro Xtra Tough Concentrate or for spot treatment use 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.

Inclusion of a weedkiller product does not indicate a recommendation or endorsement by the RHS. It is a list of products currently available to the home gardener.

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
Weeds: non-chemical control