Cold hardiness & minimum temperature

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

Also called Nikko bog rosemary.

More about nikko bog rosemary

About Nikko bog rosemary

Andromeda polifolia 'Nikko' · also called Nikko bog rosemary · flowering

Nikko bog rosemary is a Japanese-selected cultivar of Andromeda polifolia forming a neat, low mound of narrow blue-green leaves with deep pink to rosy-red urn-shaped flowers in spring. Among the most floriferous of the Andromeda cultivars, it excels in acidic bog beds, rock gardens, and troughs in cool temperate climates.

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

What nikko bog rosemary's hardiness rating actually means

Yes — nikko 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. Nikko bog rosemary is built for winter — once established it takes hard frost and snow in its stride.

Concretely, for nikko 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 nikko 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 nikko 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.

Nikko bog rosemary hardiness — frequently asked questions

Is nikko bog rosemary cold hardy?

Yes — nikko 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. Nikko 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 nikko bog rosemary can survive?

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

What hardiness zone is nikko bog rosemary?

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

Can nikko 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 nikko 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.