Cold hardiness & minimum temperature

Is Blue Ice bog rosemary (Andromeda polifolia 'Blue Ice')cold hardy? Hardiness zone & min temp

Also called Blue Ice bog rosemary, Blue Ice marsh andromeda.

More about blue ice bog rosemary

About Blue Ice bog rosemary

Andromeda polifolia 'Blue Ice' · also called Blue Ice bog rosemary, Blue Ice marsh andromeda · flowering

Blue Ice bog rosemary is a choice cultivar prized for its intensely blue-grey, glaucous evergreen foliage and shell-pink urn-shaped flowers in spring. It forms a low, spreading mound ideal for acidic bog gardens, troughs, and alpine plantings. Fully hardy and compact, it provides year-round foliage interest even when not in bloom.

Cold limit: USDA 2-6 · RHS H7 (-30°C to 25°C)

What blue ice bog rosemary's hardiness rating actually means

Yes — blue ice bog rosemary is genuinely cold hardy. Rated RHS H7 and USDA 2-6, 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 2-6 — 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. Blue Ice bog rosemary is built for winter — once established it takes hard frost and snow in its stride.

Concretely, for blue ice bog rosemary 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 blue ice bog rosemary go outside or overwinter — and where?

Plant it out within USDA 2-6 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 blue ice bog rosemary can be outside. US growers can check USDA zones; UK growers should use the RHS hardiness ratings, which match the H7 figure above.

Blue Ice bog rosemary hardiness — frequently asked questions

Is blue ice bog rosemary cold hardy?

Yes — blue ice bog rosemary is genuinely cold hardy. Rated RHS H7 and USDA 2-6, it lives outdoors all year and needs winter cold rather than protection from it. An outdoor plant. Blue Ice bog rosemary is hardy across USDA 2-6; 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 blue ice bog rosemary can survive?

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

What hardiness zone is blue ice bog rosemary?

Blue Ice bog rosemary is rated USDA 2-6 and RHS H7 — Hardy in the severest European continental winters.

Can blue ice bog rosemary survive winter outside?

Plant it out within USDA 2-6 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 blue ice bog rosemary 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.