Cold hardiness & minimum temperature

Is Masterwort 'Ruby Wedding' (Astrantia major)cold hardy? Hardiness zone & min temp

Also called Ruby Wedding Masterwort, Great Masterwort, Hattie's Pincushion.

More about masterwort 'ruby wedding'

About Masterwort 'Ruby Wedding'

Astrantia major · also called Ruby Wedding Masterwort, Great Masterwort · flowering

Masterwort 'Ruby Wedding' is a clump-forming herbaceous perennial with distinctive pincushion flower heads of deep ruby-red surrounded by papery bracts. It blooms from late spring through summer and thrives in partially shaded, moist borders. A cottage-garden classic with a long flowering season. Not considered toxic to pets.

Cold limit: USDA 4-9 · RHS H6 (-15-25°C)

What masterwort 'ruby wedding''s hardiness rating actually means

Yes — masterwort 'ruby wedding' 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. Masterwort 'Ruby Wedding' is built for winter — once established it takes hard frost and snow in its stride.

Concretely, for masterwort 'ruby wedding' 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 masterwort 'ruby wedding' 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 masterwort 'ruby wedding' can be outside. US growers can check USDA zones; UK growers should use the RHS hardiness ratings, which match the H6 figure above.

Masterwort 'Ruby Wedding' hardiness — frequently asked questions

Is masterwort 'ruby wedding' cold hardy?

Yes — masterwort 'ruby wedding' 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. Masterwort 'Ruby Wedding' 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 masterwort 'ruby wedding' can survive?

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

What hardiness zone is masterwort 'ruby wedding'?

Masterwort 'Ruby Wedding' is rated USDA 4-9 and RHS H6 — Hardy throughout the UK and northern Europe.

Can masterwort 'ruby wedding' 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 masterwort 'ruby wedding' 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.