Cold hardiness & minimum temperature

Is Hosta 'Krossa Regal' (Hosta 'Krossa Regal')cold hardy? Hardiness zone & min temp

Also called Krossa Regal hosta, Vase hosta, Regal hosta.

More about hosta 'krossa regal'

About Hosta 'Krossa Regal'

Hosta 'Krossa Regal' · also called Krossa Regal hosta, Vase hosta · flowering

Hosta 'Krossa Regal' is a large, vase-shaped shade perennial with upright, deeply corrugated, powdery blue-grey leaves and exceptionally tall flower scapes bearing lavender blooms in midsummer. Its distinctive upright habit makes it one of the most architectural hostas available. Toxic to dogs and cats.

Cold limit: USDA 3-9 · RHS H7 (5-25°C)

Watch for — Crown rot: Waterlogged soils in winter damage the dormant crown. Plant on a slight rise or in well-structured, free-draining beds.

What hosta 'krossa regal''s hardiness rating actually means

Yes — hosta 'krossa regal' is genuinely cold hardy. Rated RHS H7 and USDA 3-9, 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 3-9 — 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 below about −20 °C. Hosta 'Krossa Regal' is built for winter — once established it takes hard frost and snow in its stride.

Concretely, for hosta 'krossa regal' 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 hosta 'krossa regal' go outside or overwinter — and where?

Plant it out within USDA 3-9 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 hosta 'krossa regal' can be outside. US growers can check USDA zones; UK growers should use the RHS hardiness ratings, which match the H7 figure above.

Hosta 'Krossa Regal' hardiness — frequently asked questions

Is hosta 'krossa regal' cold hardy?

Yes — hosta 'krossa regal' is genuinely cold hardy. Rated RHS H7 and USDA 3-9, it lives outdoors all year and needs winter cold rather than protection from it. An outdoor plant. Hosta 'Krossa Regal' is hardy across USDA 3-9; 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 hosta 'krossa regal' can survive?

Minimum survivable temperature is roughly below about −20 °C. Hosta 'Krossa Regal' is built for winter — once established it takes hard frost and snow in its stride.

What hardiness zone is hosta 'krossa regal'?

Hosta 'Krossa Regal' is rated USDA 3-9 and RHS H7 — Hardy in the severest European continental winters.

Can hosta 'krossa regal' survive winter outside?

Plant it out within USDA 3-9 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 hosta 'krossa regal' 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.