Horsetail (Scouring rush)

Equisetum arvense

Prehistoric ancestor of the modern flora — the lineage is 300 million years old. Highly siliceous shoots are used in biodynamic preparations as a fungicidal foliar spray.

Hardiness ratings

Horsetail (Scouring rush) hardiness across the four zone systems
SystemRatingTemperature rangeHow to read it
USDA hardiness zone Zone 2–9 −45.6 °C to −1.1 °C Plant tolerates down to this zone
RHS hardiness rating H7 down to −20 °C Plant needs at least this level of cold tolerance
Canadian plant hardiness zone Zone 2–9 −40 °C and warmer Plant tolerates down to this zone
Australian (ANBG) zone Zone 1–5 −15 °C to 10 °C Plant tolerates down to this zone

Growing notes

  • Dynamic accumulator — concentrates silica at exceptional levels (up to 10% of dry weight)
  • EXTREMELY INVASIVE and near-impossible to eradicate once established — spreads by deep rhizomes that regenerate from any fragment. Plant only with extreme caution, ideally harvest from existing wild populations rather than introducing.
  • Equisetum tea or fermented extract used as a copper-free natural fungicide spray in biodynamic gardening

Categories

Related plants

Cross-check Horsetail (Scouring rush) against your zones

Reference

Horsetail (Scouring rush) on Wikipedia