California poppy (Eschscholzia californica) – hardiness zones in USDA, RHS, Canadian & Australian systems

Brilliant orange-flowered native of California, perennial in mild climates and an annual elsewhere. Traditional gentle sedative and analgesic.

Hardiness ratings

California poppy hardiness across the four zone systems
System	Rating	Temperature range	How to read it
USDA hardiness zone	Zone 5–10	−28.9 °C to 4.4 °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 5–9	−23 °C and warmer	Plant tolerates down to this zone
Australian (ANBG) zone	Zone 1–6	−15 °C to 15 °C	Plant tolerates down to this zone

Despite the family resemblance, unrelated to the opium poppy and contains none of its constituents — safe and gentle
Self-seeds prolifically once established
Always consult a qualified medical or herbal practitioner before using any plant medicinally