Cold hardiness & minimum temperature

Is Common Mallow (Malva sylvestris)cold hardy? Hardiness zone & min temp

Also called Common Mallow, High Mallow, Tall Mallow, Cheese Mallow.

More about common mallow

About Common Mallow

Malva sylvestris · also called Common Mallow, High Mallow · flowering

Malva sylvestris is a robust biennial or short-lived perennial wildflower native throughout Europe, North Africa, and western Asia, widely naturalised worldwide. It colonises roadsides, waste ground, and hedgebanks, preferring full sun and well-drained soils; once established its deep taproot gives exceptional drought tolerance — but it dislikes being transplanted. The showy purple-veined mauve flowers appear from June to October. Common mallow is not toxic to cats, dogs, or humans and the young leaves and unripe seed pods are traditionally eaten as food.

Cold limit: USDA 4-8 · RHS H5 (-15 to 32°C)

What common mallow's hardiness rating actually means

Yes — common mallow is genuinely cold hardy. Rated RHS H5 and USDA 4-8, 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 4-8 — 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 −15 to −10 °C. Common Mallow is built for winter — once established it takes hard frost and snow in its stride.

Concretely, for common mallow 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 mallow go outside or overwinter — and where?

Plant it out within USDA 4-8 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 common mallow can be outside. US growers can check USDA zones; UK growers should use the RHS hardiness ratings, which match the H5 figure above.

Common Mallow hardiness — frequently asked questions

Is common mallow cold hardy?

Yes — common mallow is genuinely cold hardy. Rated RHS H5 and USDA 4-8, it lives outdoors all year and needs winter cold rather than protection from it. An outdoor plant. Common Mallow is hardy across USDA 4-8; 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 common mallow can survive?

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

What hardiness zone is common mallow?

Common Mallow is rated USDA 4-8 and RHS H5 — Hardy in most of the UK and in cold winters.

Can common mallow survive winter outside?

Plant it out within USDA 4-8 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 common mallow 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.