Buckthorn — Alder

Frangula alnus

Wetland-edge European shrub. Aged bark is a stimulant laxative similar to senna; only the dried-and-aged bark is safe — fresh bark causes severe vomiting.

Hardiness ratings

Buckthorn — Alder hardiness across the four zone systems
SystemRatingTemperature rangeHow to read it
USDA hardiness zone Zone 3–7 −40 °C to −12.2 °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 3–7 −34 °C to −7 °C Plant tolerates down to this zone
Australian (ANBG) zone Zone 1–3 −15 °C to 0 °C Plant tolerates down to this zone

Growing notes

  • Critical foodplant for the brimstone butterfly larva — without alder buckthorn the brimstone disappears
  • Brilliant yellow autumn foliage — striking seasonal display
  • Stimulant laxative — same cautions as senna; not for prolonged use
  • Fresh bark must be aged at least one year (or heated) before use
  • Always consult a qualified medical or herbal practitioner before using any plant medicinally

Categories

Related plants

Cross-check Buckthorn — Alder against your zones

Reference

Buckthorn — Alder on Wikipedia