Cold hardiness & minimum temperature

Is Mountain Rimu (Dacrydium bidwillii)cold hardy? Hardiness zone & min temp

Also called Bog Pine, Mountain Pine, New Zealand Mountain Rimu.

More about mountain rimu

About Mountain Rimu

Dacrydium bidwillii · also called Bog Pine, Mountain Pine · flowering

Mountain Rimu is a compact, slow-growing podocarp conifer native to the montane and subalpine zones of New Zealand's North and South Islands. It forms a low, spreading shrub with fine, scale-like leaves. Hardy and moisture-tolerant, it suits cool temperate gardens and rock gardens. It is not on the ASPCA toxic plants list.

Cold limit: USDA 8-10 · RHS H4 (-5 to 20°C)

What mountain rimu's hardiness rating actually means

Yes — mountain rimu is genuinely cold hardy. Rated RHS H4 and USDA 8-10, it lives outdoors all year and needs winter cold rather than protection from it. Its RHS rating of H4 means: Hardy in an average winter across much of the temperate world. On the US scale that maps to USDA 8-10 — 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 −10 to −5 °C. Mountain Rimu is built for winter — once established it takes hard frost and snow in its stride.

Concretely, for mountain rimu as it gets too cold:

It tolerates winter lows to about −10 to −5 °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 mountain rimu go outside or overwinter — and where?

Plant it out within USDA 8-10 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 mountain rimu can be outside. US growers can check USDA zones; UK growers should use the RHS hardiness ratings, which match the H4 figure above.

Mountain Rimu hardiness — frequently asked questions

Is mountain rimu cold hardy?

Yes — mountain rimu is genuinely cold hardy. Rated RHS H4 and USDA 8-10, it lives outdoors all year and needs winter cold rather than protection from it. An outdoor plant. Mountain Rimu is hardy across USDA 8-10; 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 mountain rimu can survive?

Minimum survivable temperature is roughly about −10 to −5 °C. Mountain Rimu is built for winter — once established it takes hard frost and snow in its stride.

What hardiness zone is mountain rimu?

Mountain Rimu is rated USDA 8-10 and RHS H4 — Hardy in an average winter across much of the temperate world.

Can mountain rimu survive winter outside?

Plant it out within USDA 8-10 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 mountain rimu below its minimum temperature?

It tolerates winter lows to about −10 to −5 °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.