Cold hardiness & minimum temperature

Is Red crowberry (Empetrum rubrum)cold hardy? Hardiness zone & min temp

Also called Red crowberry, Crimson crowberry.

More about red crowberry

About Red crowberry

Empetrum rubrum · also called Red crowberry, Crimson crowberry · edible

A low, mat-forming evergreen shrub native to high-altitude South America, Patagonia, and Falkland Islands. Thrives in cool, acidic, peaty soils in full sun. Produces small red-purple edible berries used in jams and juices. Very cold-hardy and wind-tolerant; ideal for alpine, rock, or coastal gardens.

Cold limit: USDA 4-8 · RHS H6 (-20 to 20°C)

What red crowberry's hardiness rating actually means

Yes — red crowberry is genuinely cold hardy. Rated RHS H6 and USDA 4-8, it lives outdoors all year and needs winter cold rather than protection from it. Its RHS rating of H6 means: Hardy throughout the UK and northern Europe. On the US scale that maps to USDA 4-8 — 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 −20 to −15 °C. Red crowberry is built for winter — once established it takes hard frost and snow in its stride.

Concretely, for red crowberry as it gets too cold:

It tolerates winter lows to about −20 to −15 °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 red crowberry go outside or overwinter — and where?

Plant it out within USDA 4-8 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 red crowberry can be outside. US growers can check USDA zones; UK growers should use the RHS hardiness ratings, which match the H6 figure above.

Red crowberry hardiness — frequently asked questions

Is red crowberry cold hardy?

Yes — red crowberry is genuinely cold hardy. Rated RHS H6 and USDA 4-8, it lives outdoors all year and needs winter cold rather than protection from it. An outdoor plant. Red crowberry is hardy across USDA 4-8; 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 red crowberry can survive?

Minimum survivable temperature is roughly about −20 to −15 °C. Red crowberry is built for winter — once established it takes hard frost and snow in its stride.

What hardiness zone is red crowberry?

Red crowberry is rated USDA 4-8 and RHS H6 — Hardy throughout the UK and northern Europe.

Can red crowberry survive winter outside?

Plant it out within USDA 4-8 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 red crowberry below its minimum temperature?

It tolerates winter lows to about −20 to −15 °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.