Field horsetail
Also known as
Common horsetail, Shavegrass, Bottlebrush horsetail, Horsetail fern, Puzzlegrass
Keep this plant’s care guide close at hand.
Get the appAbout Field horsetail
Equisetum arvense, commonly called field horsetail, is a rhizomatous perennial fern ally from an ancient lineage. In early spring it produces short, tan, unbranched fertile shoots topped with a cone-like strobilus that releases spores. Later, taller sterile shoots emerge, bright green with jointed, hollow stems ringed by whorls of fine, rough-textured branchlets rich in silica. Underground, tough, cord-like rhizomes spread aggressively and can penetrate deeply, allowing the plant to colonize disturbed, compacted, or nutrient-poor soils. In nature it favors moist to wet, often acidic sites such as streambanks, marsh edges, ditches, and damp meadows, but it tolerates periodic drying once established. Because of its primitive anatomy and silica content, it was historically used as a scouring material. In gardens and containers, it lends a delicate, bamboo-like texture but can become invasive without barriers. All parts contain thiaminase; ingestion by humans or pets can be harmful, especially to horses. It is hardy in cold climates, dying back and resprouting annually.
Taxonomy
Properties & Requirements
How to care for Field horsetail
Water
Keep the substrate consistently moist to wet—never allow it to dry out completely. In containers, use a water-retentive mix and water until runoff, then allow only the surface to barely dry before watering again. Horsetail tolerates shallow standing water, so a saucer reservoir is acceptable. In very warm or windy conditions, you may need to water daily. Use softer water if possible to limit salt buildup.
Light
Provide bright light to full sun for best form; 4–6+ hours of direct sun is ideal in mild climates. In hot, arid regions, give morning sun and afternoon shade to prevent scorching and excessive evaporation. Plants grown in deep shade become lax and sparse. Indoors, place at a very bright window or under high-output grow lights 12–14 hours daily. Rotate periodically for even growth.
Nutrients
Field horsetail is adapted to lean, low-fertility substrates and typically needs minimal feeding. In containers, apply a balanced, low-phosphorus fertilizer at 1/4–1/2 strength monthly during active growth, or use a light, slow-release formulation in spring. Avoid heavy applications and high-pH, lime-containing amendments, which can reduce vigor and encourage algal growth. Flush the pot occasionally to prevent salt accumulation, especially if using tap water.
Temperature
Equisetum arvense is extremely cold-hardy (USDA Zones 3–9), dying back in winter and resprouting in spring. Actively growing shoots are comfortable between 50–80°F (10–27°C). During dormancy, rhizomes tolerate freezing well below 0°F (−18°C). Indoors, avoid hot, dry air and temperatures above 90°F (32°C), which increase water demand and can cause tip burn. Provide good airflow but protect from desiccating heaters or strong, drying winds.
