Cold hardiness & minimum temperature

Is Arborvitae (Thuja occidentalis)cold hardy? Hardiness zone & min temp

Also called arborvitae, eastern arborvitae, American arborvitae, white cedar, eastern white cedar, northern white cedar, tree of life.

More about arborvitae

About Arborvitae

Thuja occidentalis · also called arborvitae, eastern arborvitae · houseplant

Arborvitae is a hardy evergreen conifer grown outdoors for hedging, screening and in large containers. It wants full sun, deep well-drained soil and even moisture while establishing. It is not on the ASPCA list, but its foliage and oils contain thujone — a neurotoxin — so treat it as toxic to pets and livestock and verify any exposure with your vet.

Cold limit: USDA USDA zones 3-8 (some sources cite zone 2 for hardiness) · RHS H7 (fully hardy; several cultivars such as 'Smaragd' and 'Rheingold' hold the RHS Award of Garden Merit) (-40 to 30°C)

Watch for — Winter burn / foliage bronzing: Cold, drying winds and winter sun pull moisture from the evergreen foliage faster than frozen roots can replace it, scorching it brown, especially on young or exposed plants.

What arborvitae's hardiness rating actually means

Yes — arborvitae is genuinely cold hardy. Rated RHS H7 and USDA USDA zones 3-8 (some sources cite zone 2 for hardiness), 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 USDA zones 3-8 (some sources cite zone 2 for hardiness) — 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. Arborvitae is built for winter — once established it takes hard frost and snow in its stride.

Concretely, for arborvitae 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 arborvitae go outside or overwinter — and where?

Plant it out within USDA USDA zones 3-8 (some sources cite zone 2 for hardiness) 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 arborvitae can be outside. US growers can check USDA zones; UK growers should use the RHS hardiness ratings, which match the H7 figure above.

Arborvitae hardiness — frequently asked questions

Is arborvitae cold hardy?

Yes — arborvitae is genuinely cold hardy. Rated RHS H7 and USDA USDA zones 3-8 (some sources cite zone 2 for hardiness), it lives outdoors all year and needs winter cold rather than protection from it. An outdoor plant. Arborvitae is hardy across USDA USDA zones 3-8 (some sources cite zone 2 for hardiness); 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 arborvitae can survive?

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

What hardiness zone is arborvitae?

Arborvitae is rated USDA USDA zones 3-8 (some sources cite zone 2 for hardiness) and RHS H7 — Hardy in the severest European continental winters.

Can arborvitae survive winter outside?

Plant it out within USDA USDA zones 3-8 (some sources cite zone 2 for hardiness) 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 arborvitae 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.