Cold hardiness & minimum temperature

Is Salvia 'May Night' (Salvia × sylvestris 'Mainacht')cold hardy? Hardiness zone & min temp

Also called Woodland sage, May Night salvia.

More about salvia 'may night'

About Salvia 'May Night'

Salvia × sylvestris 'Mainacht' · also called Woodland sage, May Night salvia · flowering

Salvia 'May Night' is a hardy clump-forming perennial topped with dense spikes of deep indigo-violet flowers from late spring, prized by bees. Tough, drought-tolerant once established, and long-lived, it rewards a shearing after the first flush with a strong rebloom. No Salvia appears on the ASPCA toxic list.

Cold limit: USDA 4-8 · RHS H7 (15-27°C)

Watch for — Crown / root rot in wet soil: Poor winter drainage rots the crown; site in sharply drained ground and never let it sit waterlogged.

What salvia 'may night''s hardiness rating actually means

Yes — salvia 'may night' is genuinely cold hardy. Rated RHS H7 and USDA 4-8, 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 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 below about −20 °C. Salvia 'May Night' is built for winter — once established it takes hard frost and snow in its stride.

Concretely, for salvia 'may night' 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 salvia 'may night' 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 salvia 'may night' can be outside. US growers can check USDA zones; UK growers should use the RHS hardiness ratings, which match the H7 figure above.

Salvia 'May Night' hardiness — frequently asked questions

Is salvia 'may night' cold hardy?

Yes — salvia 'may night' is genuinely cold hardy. Rated RHS H7 and USDA 4-8, it lives outdoors all year and needs winter cold rather than protection from it. An outdoor plant. Salvia 'May Night' 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 salvia 'may night' can survive?

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

What hardiness zone is salvia 'may night'?

Salvia 'May Night' is rated USDA 4-8 and RHS H7 — Hardy in the severest European continental winters.

Can salvia 'may night' 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 salvia 'may night' 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.