Cold hardiness & minimum temperature

Is Sea Wormwood (Artemisia maritima)cold hardy? Hardiness zone & min temp

Also called Sea Wormwood, Old Warrior, Seriphium.

More about sea wormwood

About Sea Wormwood

Artemisia maritima · also called Sea Wormwood, Old Warrior · herb

Sea Wormwood is a compact, woody-based aromatic perennial native to European salt marshes and coastal cliffs. It produces silvery, finely cut foliage with a strong, pungent scent. Exceptional salt, wind, and drought tolerance makes it ideal for coastal gardens and gravel beds. Historically used to flavour vermouth and in herbal medicine.

Cold limit: USDA 4–8 · RHS H6 (-20°C to 35°C)

Watch for — Spider mite in hot, dry conditions: Despite liking dry conditions, the fine foliage can host spider mites in hot summers. Mist foliage with water in the evening during extreme heat; avoid indoor overwintering in low-humidity rooms.

What sea wormwood's hardiness rating actually means

Yes — sea wormwood is genuinely cold hardy. Rated RHS H6 and USDA 4–8, it lives outdoors all year and needs winter cold rather than protection from it. Its RHS rating of H6 means: Hardy throughout the UK and northern Europe. 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 −20 to −15 °C. Sea Wormwood is built for winter — once established it takes hard frost and snow in its stride.

Concretely, for sea wormwood as it gets too cold:

It tolerates winter lows to about −20 to −15 °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 sea wormwood 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 sea wormwood can be outside. US growers can check USDA zones; UK growers should use the RHS hardiness ratings, which match the H6 figure above.

Sea Wormwood hardiness — frequently asked questions

Is sea wormwood cold hardy?

Yes — sea wormwood is genuinely cold hardy. Rated RHS H6 and USDA 4–8, it lives outdoors all year and needs winter cold rather than protection from it. An outdoor plant. Sea Wormwood 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 sea wormwood can survive?

Minimum survivable temperature is roughly about −20 to −15 °C. Sea Wormwood is built for winter — once established it takes hard frost and snow in its stride.

What hardiness zone is sea wormwood?

Sea Wormwood is rated USDA 4–8 and RHS H6 — Hardy throughout the UK and northern Europe.

Can sea wormwood 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 sea wormwood below its minimum temperature?

It tolerates winter lows to about −20 to −15 °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.