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UK hardiness

Is it hardy in the UK?

RHS rating, winter survival and overwintering for 200 plants.

UK hardiness is about your garden's coldest night, not a regional map — mild coastal and urban gardens hold plants that fail inland at the same latitude. Ratings follow the RHS hardiness system. US gardener? See the USDA hardiness library.

H1b — heated glasshouse (subtropical) (54)

H1c — warm temperate, summer outdoors only (53)

H2 — tender, needs frost-free cover (23)

H3 — half-hardy, mild/coastal only (10)

H4 — hardy in an average UK winter (13)

H5 — hardy in a cold UK winter (21)

H6 — hardy in a very cold winter (16)

H7 — very hardy (below -20°C) (10)