Cold hardiness & minimum temperature

Is Common Foxglove (Digitalis purpurea)cold hardy? Hardiness zone & min temp

Also called Foxglove, Purple foxglove.

More about common foxglove

About Common Foxglove

Digitalis purpurea · also called Foxglove, Purple foxglove · flowering

Common foxglove is a stately woodland biennial that forms a leafy rosette in year one and sends up a tall one-sided spire of tubular purple-pink, freckled bells in year two. It thrives in dappled shade and moist humus-rich soil, self-seeds prolifically, and draws bumblebees. All parts are highly poisonous.

Cold limit: USDA 4-9 · RHS H5 (5-22°C)

Watch for — Crown rot in wet soil: Overwinter rosettes rot in heavy, waterlogged ground. Plant in well-drained, humus-rich soil and avoid winter wet.

What common foxglove's hardiness rating actually means

Yes — common foxglove is genuinely cold hardy. Rated RHS H5 and USDA 4-9, it lives outdoors all year and needs winter cold rather than protection from it. Its RHS rating of H5 means: Hardy in most of the UK and in cold winters. 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 −15 to −10 °C. Common Foxglove is built for winter — once established it takes hard frost and snow in its stride.

Concretely, for common foxglove as it gets too cold:

It tolerates winter lows to about −15 to −10 °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 common foxglove 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 common foxglove can be outside. US growers can check USDA zones; UK growers should use the RHS hardiness ratings, which match the H5 figure above.

Common Foxglove hardiness — frequently asked questions

Is common foxglove cold hardy?

Yes — common foxglove is genuinely cold hardy. Rated RHS H5 and USDA 4-9, it lives outdoors all year and needs winter cold rather than protection from it. An outdoor plant. Common Foxglove 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 common foxglove can survive?

Minimum survivable temperature is roughly about −15 to −10 °C. Common Foxglove is built for winter — once established it takes hard frost and snow in its stride.

What hardiness zone is common foxglove?

Common Foxglove is rated USDA 4-9 and RHS H5 — Hardy in most of the UK and in cold winters.

Can common foxglove 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 common foxglove below its minimum temperature?

It tolerates winter lows to about −15 to −10 °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.