Cold hardiness & minimum temperature

Is Selfheal (Prunella vulgaris)cold hardy? Hardiness zone & min temp

Also called Selfheal, Common Selfheal, Heal-All, All-Heal.

More about selfheal

About Selfheal

Prunella vulgaris · also called Selfheal, Common Selfheal · herb

Prunella vulgaris is a low-growing, creeping perennial herb native throughout Europe, Asia, and North America, commonly found in lawns, meadows, roadsides, and open woodland. It produces dense, squarish spikes of purple, two-lipped flowers from June to October and has been used in herbal medicine for centuries as an antiseptic and wound-healing herb, particularly in Traditional Chinese Medicine. It tolerates a wide range of soils and light conditions but performs best in moist, reasonably fertile soil with some sun. Selfheal is not known to be toxic to cats or dogs.

Cold limit: USDA 4-9 · RHS H7 (-30 °C to 25 °C)

What selfheal's hardiness rating actually means

Yes — selfheal is genuinely cold hardy. Rated RHS H7 and USDA 4-9, 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 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 below about −20 °C. Selfheal is built for winter — once established it takes hard frost and snow in its stride.

Concretely, for selfheal 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 selfheal 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 selfheal can be outside. US growers can check USDA zones; UK growers should use the RHS hardiness ratings, which match the H7 figure above.

Selfheal hardiness — frequently asked questions

Is selfheal cold hardy?

Yes — selfheal is genuinely cold hardy. Rated RHS H7 and USDA 4-9, it lives outdoors all year and needs winter cold rather than protection from it. An outdoor plant. Selfheal 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 selfheal can survive?

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

What hardiness zone is selfheal?

Selfheal is rated USDA 4-9 and RHS H7 — Hardy in the severest European continental winters.

Can selfheal 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 selfheal 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.