Cold hardiness & minimum temperature

Is Nootka Lupin (Lupinus nootkatensis)cold hardy? Hardiness zone & min temp

Also called Nootka Lupin, Alaska Lupin, Nootka Lupine.

More about nootka lupin

About Nootka Lupin

Lupinus nootkatensis · also called Nootka Lupin, Alaska Lupin · flowering

A robust, short-lived perennial or biennial lupin native to the coastal Pacific Northwest and Alaska, producing dense spikes of blue-to-violet flowers in early summer above palmate leaves. Ecologically important as a nitrogen-fixer, it can naturalise vigorously in sandy or disturbed soils. Toxic to pets and livestock due to quinolizidine alkaloids.

Cold limit: USDA 3-7 · RHS H7 (-25-20°C)

What nootka lupin's hardiness rating actually means

Yes — nootka lupin is genuinely cold hardy. Rated RHS H7 and USDA 3-7, 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 3-7 — 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 below about −20 °C. Nootka Lupin is built for winter — once established it takes hard frost and snow in its stride.

Concretely, for nootka lupin 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 nootka lupin go outside or overwinter — and where?

Plant it out within USDA 3-7 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 nootka lupin can be outside. US growers can check USDA zones; UK growers should use the RHS hardiness ratings, which match the H7 figure above.

Nootka Lupin hardiness — frequently asked questions

Is nootka lupin cold hardy?

Yes — nootka lupin is genuinely cold hardy. Rated RHS H7 and USDA 3-7, it lives outdoors all year and needs winter cold rather than protection from it. An outdoor plant. Nootka Lupin is hardy across USDA 3-7; 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 nootka lupin can survive?

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

What hardiness zone is nootka lupin?

Nootka Lupin is rated USDA 3-7 and RHS H7 — Hardy in the severest European continental winters.

Can nootka lupin survive winter outside?

Plant it out within USDA 3-7 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 nootka lupin 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.