Often grown as an ornamental plant in water gardens and along the banks of wildlife ponds, Equisetum hyemale is a remarkably hardy perennial. It is commonly known as rough horsetail, scouring rush, snake grass, Dutch rush, and pewterwort. Though it is referred to as a “rush” and is frequently mistaken for a member of the grass family, it is actually a highly specialized type of fern ally. This notable member of the Equisetaceae family is one of just 20 extant types of horsetails. It is native to the temperate zones of Asia, Europe, and North America.
Rough horsetail has some fantastic sculptural features – perfect for adding vertical structure and complexity to a pond’s edge. Its upright, stiff stalks are reminiscent of the morphology of bamboo. Rarely branched, the stems are split into multiple, distinct nodes. These are ridged with inconspicuous leaves, which create a black sheath around each of the joints. Instead of producing flowers, fertile stems develop fruiting heads at their tips. Cream to brown in color, these resemble pine cones and contain spores.
Mature rough horsetail plants typically grow to about 3 – 5 feet (0.9 – 1.5 meters) tall. A single specimen may have a spread of up to 6 feet (1.8 meters) as it can form colonies. The stems are evergreen and contain chlorophyll cells for photosynthesis. In some regions, they can maintain their appearance and grow throughout the year.
Facts, Benefits & Uses of Rough Horsetail
As a wetland plant, naturalized colonies of rough horsetail play many important roles. Their aggressive rhizomes and roots can help control erosion rates along the banks of streams and rivers. The base of the shoots can tolerate being submerged in a few inches of water, so they flourish as emergent plants in marshes, swamps, lake shores, ditches, and ponds.
Wherever native colonies have developed, they create shelter for small wild animals and serve as protective structures for their safe entry and exit into water features. The submerged portions of the plant also help protect aquatic larvae and juvenile fish. The longitudinally ridged, hollow stems increase the surface area on which beneficial microbes may spread to create a nutrient-rich biofilm.
Often used to quickly naturalize waterways, rough horsetail does not appeal to herbivores because its stiff stems contain silica. Their unpalatability and rapid rate of spread make them somewhat undesirable as a wildlife restoration plant. For this reason, horticulturists prefer to keep their colonies contained in pots and aquatic baskets. These can be arranged along one side of an outdoor pond to create a splendid backdrop. The stems also look great in Japanese gardens and urban landscapes, where they complement well-defined lines and shapes.
Rough Horsetail Growth, Hardiness & Climate
Rough horsetail is notorious for being a rapid spreader in regions outside of its native range. It spreads vegetatively, via networks of underground rhizomes and spore dispersal. Though a range of soil types and moisture conditions are tolerated, its colonies thrive best in consistently moist and fertile shorelines. It can be grown in the boggiest (poorly drained) zones of the garden, such as along the base of a slope, where little else may thrive.
Hardy to USDA zones 4 – 10, rough horsetail favors relatively cool climates in temperate zones. Its well-established colonies can persist through fairly warm conditions, however, as they can survive in temperatures up to 35˚C (95˚F). Once its stems are securely anchored to bottom substrates, they can be submerged in up to 4 inches (10 cm) of standing water. Fluctuations in water level are generally tolerated, but extended dry conditions may cause the stems to wilt.
Rough horsetail stands can compete with weeds, effectively stifling their growth. Resistant to grazing, they can be used to create a natural barrier for privacy. Do note, however, that this species may act as a host plant for insects like weevils and sawflies.
How to Plant Rough Horsetail
As rough horsetail produces spores instead of seeds, it is usually grown using rhizome divisions. To encourage them to produce new stems, situate the rhizomes below at least 2 inches (5 cm) of soil. If you’ve managed to obtain a nursery-grown specimen with young stems, you may outplant the pot or the rhizome into its permanent location. The surrounding soil line should be level with the base of the stems.
Once the rhizome is secure, make sure to moisten the soil. You may also use a pre-moistened mix when creating a container setup for clusters. Make sure to space out divisions as they will naturally produce spreading roots and may crowd out the container over time. Rhizome divisions that have yet to produce stems do not need to be submerged in standing water. As they become more securely anchored to the soil, these may be exposed to a gradually increasing depth.
How to Care for Rough Horsetail
Though rough horsetail roots will survive through brief periods of dryness, it’s advisable to keep them exposed to moist or wet conditions. Rich topsoil should bring out the best qualities of the stems, making them appear to glow with health under full sun. With proper care, a bounty of new shoots should emerge around older stems in spring. In contained setups, a horsetail stand can become increasingly dense.
In summer, direct sun may cause parched horsetail stems to grow scorched or die back; make sure they are provided with ample soil moisture and humidity during this time. Additional shade may also be appreciated in zones with dry conditions. Remove stems that have grown brown or have died back. Do not let them rot in their containers as decaying tissues may invite parasites and disease. To prevent overcrowding, you may divide and replant the rhizomes every few years.
How to Winter Rough Horsetail
Rough horsetail stems are usually able to persist through moderate to warm winters. Though their growth and spread rate may slow down due to minimized sun exposure and low temperatures, they should remain evergreen. The abrasive stems are remarkably cold-hardy and may persist through brief periods of frost, so winter care is seldom of primary concern.
Cold protection, in the form of mulch or straw, should help prevent any damage to the rhizomes. Though they are likely to survive even without protection, damaged rhizomes may fail to produce new stalks in spring. Before the first freeze of fall, make sure to thoroughly moisten the soil around horsetail stands.
Is Rough Horsetail Invasive or Toxic?
Equisetum hyemale, along with many of its hardy relatives, is known for being an invasive species outside of its native range. Its colonies aggressively compete with slow-growing plants for space and nutrients. As they can tolerate a wide range of environmental conditions and climate types, they are often successful. They can alter entire habitats, disrupting their ecological balance and reducing their overall diversity.
For these reasons, rough horsetail should only be grown in areas where both its spores and roots can be contained. Keep in mind, however, that although physical barriers can prevent its roots from spreading, any animals that visit your garden or pond may act as dispersal agents for its spores. Uncontrolled colonies of horsetail can ruin pasturelands.
This species may continually crop up as a weed along roadsides and disturbed habitats. Its runners are extremely difficult to remove. Its similarly invasive relatives (i.e. E. arvense, E. palustre, and E. ramosissimum) are now strictly prohibited in some countries. Moreover, it contains toxic properties and is unpalatable. It is known for bioaccumulating heavy metals like iron, zinc, lead, and copper.
Is Rough Horsetail Edible? Do Animals Eat It?
Rough horsetail is not an edible species and is generally avoided by herbivores and grazers. Parts of its dried stems are sometimes inadvertently incorporated into hay and are ingested by livestock, which are likely to experience problematic symptoms. Do not grow this species in farmlands or close to zones that are frequented by grazing wild animals. In gardens, place this plant in elevated containers so that pets are less likely to attempt to eat or play with its stems.
Where to Buy Rough Horsetail & Seeds? (UK & US)
Equisetum hyemale can be purchased from plant nurseries and aquascaping stores throughout its native range. It is also often carried by online plant portals. As this species is known for being invasive, make sure to check your locality’s list of prohibited plants before making a purchase. If you are located outside of its natural range, try to opt for native, slow-growing alternatives.
