Cold hardiness & minimum temperature

Is Woolly Foxglove (Digitalis lanata)cold hardy? Hardiness zone & min temp

Also called Woolly Foxglove, Grecian Foxglove, Digitalis.

More about woolly foxglove

About Woolly Foxglove

Digitalis lanata · also called Woolly Foxglove, Grecian Foxglove · herb

Woolly Foxglove is a biennial or short-lived perennial from the Balkans and southeastern Europe, cultivated commercially as the primary source of the cardiac glycoside digoxin. It produces dense spikes of creamy-white, brown-veined tubular flowers in its second year. All parts are highly toxic. Suited to sunny, well-drained borders; moderately drought-tolerant once established.

Cold limit: USDA 4-9 · RHS H5 (2-25°C)

Watch for — Crown rot in wet winters: The basal rosette is susceptible to rotting in waterlogged soil over winter. Improve drainage before planting; avoid heavy mulching over the crown. In containers, ensure drainage holes are clear.

What woolly foxglove's hardiness rating actually means

Yes — woolly 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. Woolly Foxglove is built for winter — once established it takes hard frost and snow in its stride.

Concretely, for woolly 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 woolly 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 woolly foxglove can be outside. US growers can check USDA zones; UK growers should use the RHS hardiness ratings, which match the H5 figure above.

Woolly Foxglove hardiness — frequently asked questions

Is woolly foxglove cold hardy?

Yes — woolly 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. Woolly 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 woolly foxglove can survive?

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

What hardiness zone is woolly foxglove?

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

Can woolly 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 woolly 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.