Cold hardiness & minimum temperature

Is Creeping Comfrey (Symphytum grandiflorum)cold hardy? Hardiness zone & min temp

Also called Creeping Comfrey, Ground Cover Comfrey, Dwarf Comfrey.

More about creeping comfrey

About Creeping Comfrey

Symphytum grandiflorum · also called Creeping Comfrey, Ground Cover Comfrey · flowering

Creeping Comfrey is a low-growing, mat-forming perennial valued as a tough, weed-suppressing ground cover under trees and in shaded borders. Cream to pale-yellow tubular flowers emerge in early spring, often before the leaves fully expand. Virtually maintenance-free once established, it tolerates deep shade and dry soil better than most Symphytum species.

Cold limit: USDA 3–9 · RHS H7 (-25 to 22°C)

What creeping comfrey's hardiness rating actually means

Yes — creeping comfrey is genuinely cold hardy. Rated RHS H7 and USDA 3–9, 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 3–9 — 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. Creeping Comfrey is built for winter — once established it takes hard frost and snow in its stride.

Concretely, for creeping comfrey 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 creeping comfrey go outside or overwinter — and where?

Plant it out within USDA 3–9 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 creeping comfrey can be outside. US growers can check USDA zones; UK growers should use the RHS hardiness ratings, which match the H7 figure above.

Creeping Comfrey hardiness — frequently asked questions

Is creeping comfrey cold hardy?

Yes — creeping comfrey is genuinely cold hardy. Rated RHS H7 and USDA 3–9, it lives outdoors all year and needs winter cold rather than protection from it. An outdoor plant. Creeping Comfrey is hardy across USDA 3–9; 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 creeping comfrey can survive?

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

What hardiness zone is creeping comfrey?

Creeping Comfrey is rated USDA 3–9 and RHS H7 — Hardy in the severest European continental winters.

Can creeping comfrey survive winter outside?

Plant it out within USDA 3–9 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 creeping comfrey 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.