Cold hardiness & minimum temperature

Is Bitterroot (Lewisia rediviva)cold hardy? Hardiness zone & min temp

Also called Bitterroot, Resurrection Plant, Tobacco Root.

More about bitterroot

About Bitterroot

Lewisia rediviva · also called Bitterroot, Resurrection Plant · flowering

The state flower of Montana, Lewisia rediviva is a striking deciduous alpine wildflower bearing large, showy pink to white flowers in late spring on bare ground, long after the narrow, succulent winter leaves have withered. Completely summer-dormant, it requires desert-dry conditions after bloom and is exceptionally cold-hardy but intolerant of summer moisture.

Cold limit: USDA 3–8 · RHS H7 (-25 to 30°C)

Watch for — Extremely difficult in cultivation outside native range: Very hard to keep long-term in areas with wet summers or mild winters. Best approached as an alpine house specimen or grown in deep terracotta pots that can be completely withheld from summer rain.

What bitterroot's hardiness rating actually means

Yes — bitterroot is genuinely cold hardy. Rated RHS H7 and USDA 3–8, it lives outdoors all year and needs winter cold rather than protection from it. Its RHS rating of H7 means: Hardy in the severest European continental winters. On the US scale that maps to USDA 3–8 — the zones where it can be left outdoors year-round.

New to these scales? The USDA hardiness zone map explained covers how the zone numbers work, and you can find your own zone with the zone finder.

Minimum temperature — and what happens below it

Minimum survivable temperature is roughly below about −20 °C. Bitterroot is built for winter — once established it takes hard frost and snow in its stride.

Concretely, for bitterroot as it gets too cold:

It tolerates winter lows to about −20 °C once established.
Below its rated zone, the visible damage is browned or blackened top growth and, in the worst case, a killed crown or root.
First-year, newly planted, or container-grown specimens are noticeably less hardy than established garden plants — the roots are exposed.

Can bitterroot go outside or overwinter — and where?

Plant it out within USDA 3–8 and it overwinters with little or no help.
It does not want to come indoors — a warm winter room actually weakens a hardy plant by denying it dormancy.
The real risks in its range are waterlogging, wind-rock on young plants, and a late hard frost on new growth — not ordinary winter cold.

Work back from your local frost dates with the frost-date calculator: the last spring frost and first autumn frost are what really decide when bitterroot can be outside. US growers can check USDA zones; UK growers should use the RHS hardiness ratings, which match the H7 figure above.

Bitterroot hardiness — frequently asked questions

Is bitterroot cold hardy?

Yes — bitterroot is genuinely cold hardy. Rated RHS H7 and USDA 3–8, it lives outdoors all year and needs winter cold rather than protection from it. An outdoor plant. Bitterroot is hardy across USDA 3–8; it belongs in the ground or a frost-proof container, not on a windowsill, and many types actively need a cold winter to perform.

What is the minimum temperature bitterroot can survive?

Minimum survivable temperature is roughly below about −20 °C. Bitterroot is built for winter — once established it takes hard frost and snow in its stride.

What hardiness zone is bitterroot?

Bitterroot is rated USDA 3–8 and RHS H7 — Hardy in the severest European continental winters.

Can bitterroot survive winter outside?

Plant it out within USDA 3–8 and it overwinters with little or no help. It does not want to come indoors — a warm winter room actually weakens a hardy plant by denying it dormancy. The real risks in its range are waterlogging, wind-rock on young plants, and a late hard frost on new growth — not ordinary winter cold.

What happens to bitterroot below its minimum temperature?

It tolerates winter lows to about −20 °C once established. Below its rated zone, the visible damage is browned or blackened top growth and, in the worst case, a killed crown or root. First-year, newly planted, or container-grown specimens are noticeably less hardy than established garden plants — the roots are exposed.