Cold hardiness & minimum temperature

Is Cusick's Camas (Camassia cusickii)cold hardy? Hardiness zone & min temp

Also called Cusick's camas, Cusick's camass, Wild blue hyacinth.

More about cusick's camas

About Cusick's Camas

Camassia cusickii · also called Cusick's camas, Cusick's camass · flowering

Camassia cusickii is a robust bulbous perennial endemic to a restricted area of northeastern Oregon and adjacent Idaho, where it grows in seasonally wet meadows and along stream margins at elevation, producing tall spikes of pale icy-blue to lavender flowers in mid-spring. It is the largest-bulbed Camassia species and one of the most impressive for naturalising in moist borders or lightly shaded woodland edges. The most important care fact is to ensure consistently moist — but not waterlogged — soil during the growing season, then allow summer dry-down as the foliage fades. Its toxicity status is uncertain; treat as mildly toxic and keep corms away from pets.

Cold limit: USDA 5-8 · RHS H5 (-20–25°C)

What cusick's camas's hardiness rating actually means

Yes — cusick's camas is genuinely cold hardy. Rated RHS H5 and USDA 5-8, 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 5-8 — 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 about −15 to −10 °C. Cusick's Camas is built for winter — once established it takes hard frost and snow in its stride.

Concretely, for cusick's camas 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 cusick's camas go outside or overwinter — and where?

Plant it out within USDA 5-8 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 cusick's camas can be outside. US growers can check USDA zones; UK growers should use the RHS hardiness ratings, which match the H5 figure above.

Cusick's Camas hardiness — frequently asked questions

Is cusick's camas cold hardy?

Yes — cusick's camas is genuinely cold hardy. Rated RHS H5 and USDA 5-8, it lives outdoors all year and needs winter cold rather than protection from it. An outdoor plant. Cusick's Camas is hardy across USDA 5-8; 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 cusick's camas can survive?

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

What hardiness zone is cusick's camas?

Cusick's Camas is rated USDA 5-8 and RHS H5 — Hardy in most of the UK and in cold winters.

Can cusick's camas survive winter outside?

Plant it out within USDA 5-8 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 cusick's camas 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.