Cold hardiness & minimum temperature

Is Coral Bells 'Palace Purple' (Heuchera micrantha)cold hardy? Hardiness zone & min temp

Also called Coral Bells, Alumroot, Palace Purple Heuchera.

More about coral bells 'palace purple'

About Coral Bells 'Palace Purple'

Heuchera micrantha · also called Coral Bells, Alumroot · flowering

Heuchera 'Palace Purple' is a shade-tolerant perennial grown primarily for its striking deep bronze-purple foliage that remains ornamental all season. Delicate airy sprays of tiny white-cream flowers appear in summer. It thrives in partial shade with well-drained, humus-rich soil. Generally considered non-toxic to pets by the ASPCA.

Cold limit: USDA 4-9 · RHS H6 (-15-28°C)

Watch for — Heaving: Frost can push crowns out of the soil; firm back in spring and mulch around (not over) the crown before winter.

What coral bells 'palace purple''s hardiness rating actually means

Yes — coral bells 'palace purple' is genuinely cold hardy. Rated RHS H6 and USDA 4-9, 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 4-9 — 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. Coral Bells 'Palace Purple' is built for winter — once established it takes hard frost and snow in its stride.

Concretely, for coral bells 'palace purple' 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 coral bells 'palace purple' go outside or overwinter — and where?

Plant it out within USDA 4-9 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 coral bells 'palace purple' can be outside. US growers can check USDA zones; UK growers should use the RHS hardiness ratings, which match the H6 figure above.

Coral Bells 'Palace Purple' hardiness — frequently asked questions

Is coral bells 'palace purple' cold hardy?

Yes — coral bells 'palace purple' is genuinely cold hardy. Rated RHS H6 and USDA 4-9, it lives outdoors all year and needs winter cold rather than protection from it. An outdoor plant. Coral Bells 'Palace Purple' is hardy across USDA 4-9; 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 coral bells 'palace purple' can survive?

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

What hardiness zone is coral bells 'palace purple'?

Coral Bells 'Palace Purple' is rated USDA 4-9 and RHS H6 — Hardy throughout the UK and northern Europe.

Can coral bells 'palace purple' survive winter outside?

Plant it out within USDA 4-9 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 coral bells 'palace purple' 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.