Cold hardiness & minimum temperature

Is Strawberry Foxglove (Digitalis × mertonensis)cold hardy? Hardiness zone & min temp

Also called Merton foxglove, Strawberry foxglove.

More about strawberry foxglove

About Strawberry Foxglove

Digitalis × mertonensis · also called Merton foxglove, Strawberry foxglove · flowering

Strawberry foxglove is a sterile hybrid between Digitalis purpurea and D. grandiflora, valued as a reliable clump-forming perennial. It bears spikes of large, coppery strawberry-pink bells over glossy dark foliage and, being seed-sterile, lives longer than common foxglove and divides easily. It enjoys part shade and moist, rich soil; all parts are poisonous.

Cold limit: USDA 3-8 · RHS H6 (5-22°C)

Watch for — Crown rot in wet soil: Heavy, waterlogged winter soil rots the perennial crown. Plant in free-draining, humus-rich ground and avoid winter wet.

What strawberry foxglove's hardiness rating actually means

Yes — strawberry foxglove is genuinely cold hardy. Rated RHS H6 and USDA 3-8, 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 3-8 — 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. Strawberry Foxglove is built for winter — once established it takes hard frost and snow in its stride.

Concretely, for strawberry foxglove 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 strawberry foxglove go outside or overwinter — and where?

Plant it out within USDA 3-8 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 strawberry foxglove can be outside. US growers can check USDA zones; UK growers should use the RHS hardiness ratings, which match the H6 figure above.

Strawberry Foxglove hardiness — frequently asked questions

Is strawberry foxglove cold hardy?

Yes — strawberry foxglove is genuinely cold hardy. Rated RHS H6 and USDA 3-8, it lives outdoors all year and needs winter cold rather than protection from it. An outdoor plant. Strawberry Foxglove is hardy across USDA 3-8; 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 strawberry foxglove can survive?

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

What hardiness zone is strawberry foxglove?

Strawberry Foxglove is rated USDA 3-8 and RHS H6 — Hardy throughout the UK and northern Europe.

Can strawberry foxglove survive winter outside?

Plant it out within USDA 3-8 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 strawberry foxglove 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.