Purple loosestrife (Lythrum salicaria) – hardiness zones in USDA, RHS, Canadian & Australian systems

Tall native wetland perennial with spectacular spires of magenta flowers in late summer. Outstanding bee plant in its native range.

Hardiness ratings

Purple loosestrife hardiness across the four zone systems
System	Rating	Temperature range	How 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 1–6	−15 °C to 15 °C	Plant tolerates down to this zone

Outstanding bee forage and larval food plant for several specialist moth species
Magenta flower spires in late summer and early autumn are a key seasonal marker of wetland margins
WARNING: Highly invasive in North America — has devastated wetland ecosystems across Canada and the northern United States, banned in many US states, DO NOT plant in North America under any circumstances
Within its native UK and European range it is a key wildlife plant