Cold hardiness & minimum temperature

Is Rosemary (Salvia rosmarinus)cold hardy? Hardiness zone & min temp

Also called common rosemary, garden rosemary.

About Rosemary

Salvia rosmarinus · also called common rosemary, garden rosemary · herb

Rosemary is a Mediterranean evergreen shrub with needle-like aromatic leaves used widely in cooking. It loves sun and free-draining soil and dislikes wet feet, especially in winter. Hardy in mild climates; container-grown elsewhere. Pet-safe by ASPCA standards.

Rosemary, Salvia rosmarinus (formerly Rosmarinus officinalis, family Lamiaceae), is native to the Mediterranean basin and adjacent dry parts of southern Europe, North Africa and western Asia, growing wild in hot, dry, rocky scrubland.

An evergreen woody subshrub that develops woody lower stems with age; it tolerates drought, salt, heavy pruning and partial shade, but most common forms are only moderately cold-hardy and need protection or 'Arp'-type hardy cultivars in cold-winter regions.

Cold limit: USDA 7-10 · RHS H4 (10-27°C)

Watch for — Browning from the inside: Winter wet — rosemary rots in cold soggy soil.

Sources: plants.ces.ncsu.edu, missouribotanicalgarden.org, kew.org

What rosemary's hardiness rating actually means

Yes — rosemary is genuinely cold hardy. Rated RHS H4 and USDA 7-10, it lives outdoors all year and needs winter cold rather than protection from it. Its RHS rating of H4 means: Hardy in an average winter across much of the temperate world. On the US scale that maps to USDA 7-10 — 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 −10 to −5 °C. Rosemary is built for winter — once established it takes hard frost and snow in its stride.

Concretely, for rosemary as it gets too cold:

It tolerates winter lows to about −10 to −5 °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 rosemary go outside or overwinter — and where?

Plant it out within USDA 7-10 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 rosemary can be outside. US growers can check USDA zones; UK growers should use the RHS hardiness ratings, which match the H4 figure above.

Frost protection for borderline rosemary

Rosemary is right on a hardiness edge in many gardens, so if you are pushing it, these measures buy it the margin it needs:

At the cold edge of its range, mulch the root zone in late autumn to buffer the deepest freezes.
Protect container specimens — pots freeze through far faster than open ground, costing roughly a zone of hardiness.
Shelter new growth from late spring frosts with fleece if a hard night is forecast.

Rosemary hardiness — frequently asked questions

Is rosemary cold hardy?

Yes — rosemary is genuinely cold hardy. Rated RHS H4 and USDA 7-10, it lives outdoors all year and needs winter cold rather than protection from it. An outdoor plant. Rosemary is hardy across USDA 7-10; 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 rosemary can survive?

Minimum survivable temperature is roughly about −10 to −5 °C. Rosemary is built for winter — once established it takes hard frost and snow in its stride.

What hardiness zone is rosemary?

Rosemary is rated USDA 7-10 and RHS H4 — Hardy in an average winter across much of the temperate world.

Can rosemary survive winter outside?

Plant it out within USDA 7-10 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.

How do I protect rosemary from frost?

At the cold edge of its range, mulch the root zone in late autumn to buffer the deepest freezes. Protect container specimens — pots freeze through far faster than open ground, costing roughly a zone of hardiness. Shelter new growth from late spring frosts with fleece if a hard night is forecast.