R. ponticum
Description: Large species, brought to Europe by the Romans and came to England in 1763. An extremely tough plant, sun and heat tolerant. We do not stock it, as it is such an invasive weed, smothering natural habitats. Purple flowers.
Ultimate Height: 7.0 meters after 10 years
Flowering Period: This plants flowers in the North Hemisphere around April - June
Availability:  This plant is not available at present
Hardiness
UK Zone
4
RHS Zone
H (Fully Hardy)
EGF Zone
H2
US Zone
7A
Min Temp
-18°C (0°F)
Hardy in all but the coldest parts of Pacific Northwest and UK, France and northern Italy, around Bergen (Norway) and mildest parts of NE USA such as Cape Cod and parts of Long Island. (Please note.)