Common milkweed

Asclepias syriaca

Tall North American native with fragrant pink-mauve flower clusters and milky sap. The keystone larval food plant of the monarch butterfly.

Hardiness ratings

Common milkweed hardiness across the four zone systems
SystemRatingTemperature rangeHow to read it
USDA hardiness zone Zone 3–9 −40 °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 3–8 −34 °C to −1 °C 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

  • Sole larval food source for the monarch butterfly — also feeds queen and soldier butterflies
  • Fragrant flowers are exceptional bee forage
  • Contains toxic cardiac glycosides that monarch caterpillars sequester to make themselves unpalatable to predators
  • Milky sap can irritate skin and eyes — wear gloves when cutting back

Pet caution: Common milkweed is listed as potentially harmful to cats and/or dogs. Keep pets from grazing on it, and contact a vet if you suspect your animal has eaten some.

Categories

Related plants

Cross-check Common milkweed against your zones

Reference

Common milkweed on Wikipedia