Cold hardiness & minimum temperature

Is Salvia × sylvestris 'Blauhügel' (Salvia × sylvestris 'Blauhügel')cold hardy? Hardiness zone & min temp

Also called Blue Hill sage, Blue Mound salvia.

More about salvia × sylvestris 'blauhügel'

About Salvia × sylvestris 'Blauhügel'

Salvia × sylvestris 'Blauhügel' · also called Blue Hill sage, Blue Mound salvia · flowering

'Blauhügel' (Blue Hill) is a neat, mound-forming hardy sage carrying clear pure-blue flower spikes without the purple tones of darker cultivars. Compact and long-blooming, it suits the front of a sunny, well-drained border, attracts bees and butterflies, and rebounds strongly when deadheaded or sheared after its first flush.

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

Watch for — Crown rot in wet soil: Poor winter drainage rots the base. Grow in sharply drained soil and keep mulch clear of the crown.

What salvia × sylvestris 'blauhügel''s hardiness rating actually means

Yes — salvia × sylvestris 'blauhügel' 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 × sylvestris 'Blauhügel' is built for winter — once established it takes hard frost and snow in its stride.

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

Salvia × sylvestris 'Blauhügel' hardiness — frequently asked questions

Is salvia × sylvestris 'blauhügel' cold hardy?

Yes — salvia × sylvestris 'blauhügel' 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 × sylvestris 'Blauhügel' 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 × sylvestris 'blauhügel' can survive?

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

What hardiness zone is salvia × sylvestris 'blauhügel'?

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

Can salvia × sylvestris 'blauhügel' 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 × sylvestris 'blauhügel' 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.