Cold hardiness & minimum temperature

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

Also called May Night salvia, May Night sage.

More about may night salvia

About May Night Salvia

Salvia nemorosa 'Mainacht' · also called May Night salvia, May Night sage · flowering

May Night is a compact, clump-forming hardy perennial sage prized for dense spikes of deep indigo-violet flowers from late spring into summer. The 1997 Perennial Plant of the Year, it thrives in full sun and lean, well-drained soil, draws bees and butterflies, and rebounds with a second flush after a hard deadheading shear.

Cold limit: USDA 4-8 · RHS H7 (15-25°C in active growth, hardy to about -20°C dormant)

Watch for — Crown and root rot: Triggered by wet, poorly drained soil, especially over winter. Plant in sharply drained soil and never let the crown sit in standing water.

What may night salvia's hardiness rating actually means

Yes — may night salvia 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. May Night Salvia is built for winter — once established it takes hard frost and snow in its stride.

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

May Night Salvia hardiness — frequently asked questions

Is may night salvia cold hardy?

Yes — may night salvia 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. May Night Salvia 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 may night salvia can survive?

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

What hardiness zone is may night salvia?

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

Can may night salvia 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 may night salvia 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.