Cold hardiness & minimum temperature

Is Vervain (Verbena officinalis)cold hardy? Hardiness zone & min temp

Also called Vervain, Common Vervain, Herb of Grace, Herb of the Cross.

More about vervain

About Vervain

Verbena officinalis · also called Vervain, Common Vervain · herb

Verbena officinalis is a slender, wiry perennial herb native to Europe, North Africa, and western Asia, and the only verbena truly native to the British Isles. It favours chalky, disturbed, or rough ground in full sun, producing tiny lilac-pink flowers in airy branched spikes from midsummer to early autumn. The single most important care point is drainage — it resents heavy or waterlogged soil. It is not listed on the ASPCA toxic plant database and is generally considered non-toxic to cats and dogs, though it should not be confused with lemon verbena (Aloysia triphylla), which is toxic.

Cold limit: USDA 4-9 · RHS H5 (-20 to 30°C)

What vervain's hardiness rating actually means

Yes — vervain is genuinely cold hardy. Rated RHS H5 and USDA 4-9, 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 4-9 — 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 about −15 to −10 °C. Vervain is built for winter — once established it takes hard frost and snow in its stride.

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

Plant it out within USDA 4-9 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 vervain can be outside. US growers can check USDA zones; UK growers should use the RHS hardiness ratings, which match the H5 figure above.

Vervain hardiness — frequently asked questions

Is vervain cold hardy?

Yes — vervain is genuinely cold hardy. Rated RHS H5 and USDA 4-9, it lives outdoors all year and needs winter cold rather than protection from it. An outdoor plant. Vervain is hardy across USDA 4-9; 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 vervain can survive?

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

What hardiness zone is vervain?

Vervain is rated USDA 4-9 and RHS H5 — Hardy in most of the UK and in cold winters.

Can vervain survive winter outside?

Plant it out within USDA 4-9 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 vervain 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.