Cold hardiness & minimum temperature

Is Camas (Camassia quamash)cold hardy? Hardiness zone & min temp

Also called Camas, Quamash, Common Camas, Blue Camas.

More about camas

About Camas

Camassia quamash · also called Camas, Quamash · flowering

A native North American bulb bearing tall spikes of violet-blue to deep blue star-shaped flowers in late spring. Historically a vital food source for many Indigenous peoples of the Pacific Northwest. Thrives in moist meadow soils and naturalises well in borders and prairies. Deer and rodent resistant. Hardy to zone 3. Not toxic to pets.

Cold limit: USDA 3-8 · RHS H7 (-35°C to 25°C; dormant in summer)

What camas's hardiness rating actually means

Yes — camas 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. Camas is built for winter — once established it takes hard frost and snow in its stride.

Concretely, for camas 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 camas 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 camas can be outside. US growers can check USDA zones; UK growers should use the RHS hardiness ratings, which match the H7 figure above.

Camas hardiness — frequently asked questions

Is camas cold hardy?

Yes — camas 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. Camas 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 camas can survive?

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

What hardiness zone is camas?

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

Can camas 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 camas 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.