Cold hardiness & minimum temperature

Is Nevada Lewisia (Lewisia nevadensis)cold hardy? Hardiness zone & min temp

Also called Nevada Lewisia, Nevada Bitterroot.

More about nevada lewisia

About Nevada Lewisia

Lewisia nevadensis · also called Nevada Lewisia, Nevada Bitterroot · flowering

Found in moist mountain meadows, streambanks, and subalpine grasslands throughout the western United States, Lewisia nevadensis is a deciduous, taproot-forming alpine perennial that produces a rosette of narrow, fleshy leaves and starry white to pale pink flowers in late spring. Unlike the evergreen L. cotyledon, it goes completely dormant after flowering and must be kept dry during summer to prevent the taproot rotting. The most critical care point is allowing the plant to experience natural summer drought during dormancy. Lewisia is not listed by the ASPCA; classified as mildly-toxic as a precaution.

Cold limit: USDA 4-7 · RHS H5 (-20 to 25°C)

What nevada lewisia's hardiness rating actually means

Yes — nevada lewisia is genuinely cold hardy. Rated RHS H5 and USDA 4-7, it lives outdoors all year and needs winter cold rather than protection from it. Its RHS rating of H5 means: Hardy in most of the UK and in cold winters. On the US scale that maps to USDA 4-7 — 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 about −15 to −10 °C. Nevada Lewisia is built for winter — once established it takes hard frost and snow in its stride.

Concretely, for nevada lewisia as it gets too cold:

It tolerates winter lows to about −15 to −10 °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 nevada lewisia go outside or overwinter — and where?

Plant it out within USDA 4-7 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 nevada lewisia can be outside. US growers can check USDA zones; UK growers should use the RHS hardiness ratings, which match the H5 figure above.

Nevada Lewisia hardiness — frequently asked questions

Is nevada lewisia cold hardy?

Yes — nevada lewisia is genuinely cold hardy. Rated RHS H5 and USDA 4-7, it lives outdoors all year and needs winter cold rather than protection from it. An outdoor plant. Nevada Lewisia is hardy across USDA 4-7; 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 nevada lewisia can survive?

Minimum survivable temperature is roughly about −15 to −10 °C. Nevada Lewisia is built for winter — once established it takes hard frost and snow in its stride.

What hardiness zone is nevada lewisia?

Nevada Lewisia is rated USDA 4-7 and RHS H5 — Hardy in most of the UK and in cold winters.

Can nevada lewisia survive winter outside?

Plant it out within USDA 4-7 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 nevada lewisia below its minimum temperature?

It tolerates winter lows to about −15 to −10 °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.