Cold hardiness & minimum temperature

Is Interrupted Sage (Salvia interrupta)cold hardy? Hardiness zone & min temp

Also called Interrupted Sage, Moroccan Sage.

More about interrupted sage

About Interrupted Sage

Salvia interrupta · also called Interrupted Sage, Moroccan Sage · flowering

Salvia interrupta is a woody-based perennial native to rocky hillsides and scrubland in Morocco and Algeria, producing distinctive bicoloured flowers — typically blue-violet with a white patch — on tall, interrupted spikes that give the species its common name. It suits a sheltered, sunny border in mild gardens or a cool greenhouse in colder climates, requiring excellent drainage above all else. The most important care fact is that although it can tolerate moderate frost when dry, wet winter soil at the roots is invariably fatal. The plant is considered mildly toxic to pets in common with other Salvia species.

Cold limit: USDA 8-10 · RHS H3 (15–32°C in growing season; tolerates brief dry frosts to about -5°C)

Watch for — Winter wet crown rot: The leading cause of plant loss in UK and northern US gardens; mulch the crown with coarse grit in autumn, ensure the planting site drains freely, and consider lifting pot-grown plants under cover from November to March.

What interrupted sage's hardiness rating actually means

Interrupted Sage is half-hardy (RHS H3). It survives a mild winter outdoors in a sheltered spot, but a hard frost kills it — so in colder zones it is lifted, potted, or grown as a tender plant. Its RHS rating of H3 means: Half-hardy — comes through mild UK winters outside but is killed by a hard freeze. On the US scale that maps to USDA 8-10 — 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 −5 to 1 °C — a light, short frost only. Interrupted Sage shrugs off cold nights but a real, sustained freeze will kill it.

Concretely, for interrupted sage as it gets too cold:

Down to roughly about −5 to 1 °C it copes, especially if dry and sheltered.
A sustained hard frost collapses the top growth; whether it returns depends on whether the roots, crown or tubers froze.
Wet cold is far more lethal than dry cold for this plant — soggy, frozen soil is the usual killer.

Can interrupted sage go outside or overwinter — and where?

It can live outside year-round only in the mildest, most sheltered part of USDA 8-10 or a frost-free UK microclimate.
In colder zones, grow it in a pot you can move under cover, or lift its tubers/roots and store them frost-free over winter.
A south-facing wall, free-draining soil and a dry winter position can push it a full zone hardier than the books suggest.

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 interrupted sage can be outside. US growers can check USDA zones; UK growers should use the RHS hardiness ratings, which match the H3 figure above.

Frost protection for borderline interrupted sage

Interrupted Sage is right on a hardiness edge in many gardens, so if you are pushing it, these measures buy it the margin it needs:

Mulch the crown or root zone deeply with bark, straw or leaf-mould before the first hard frost.
Move container plants against a warm wall or into an unheated but frost-free porch or greenhouse.
Fleece the top growth on the coldest nights, and keep it on the dry side — dry roots survive cold far better than wet ones.
Lift dahlia-type tubers or tender crowns after the first light frost blackens the foliage and store them somewhere cool but frost-free.

Interrupted Sage hardiness — frequently asked questions

Is interrupted sage cold hardy?

Interrupted Sage is half-hardy (RHS H3). It survives a mild winter outdoors in a sheltered spot, but a hard frost kills it — so in colder zones it is lifted, potted, or grown as a tender plant. Borderline outdoors. In its mild end of USDA 8-10 (and sheltered UK gardens) interrupted sage can stay out; in colder areas it must be lifted, brought in, or treated as a frost-tender plant.

What is the minimum temperature interrupted sage can survive?

Minimum survivable temperature is roughly about −5 to 1 °C — a light, short frost only. Interrupted Sage shrugs off cold nights but a real, sustained freeze will kill it.

What hardiness zone is interrupted sage?

Interrupted Sage is rated USDA 8-10 and RHS H3 — Half-hardy — comes through mild UK winters outside but is killed by a hard freeze.

Can interrupted sage survive winter outside?

It can live outside year-round only in the mildest, most sheltered part of USDA 8-10 or a frost-free UK microclimate. In colder zones, grow it in a pot you can move under cover, or lift its tubers/roots and store them frost-free over winter. A south-facing wall, free-draining soil and a dry winter position can push it a full zone hardier than the books suggest.

How do I protect interrupted sage from frost?

Mulch the crown or root zone deeply with bark, straw or leaf-mould before the first hard frost. Move container plants against a warm wall or into an unheated but frost-free porch or greenhouse. Fleece the top growth on the coldest nights, and keep it on the dry side — dry roots survive cold far better than wet ones. Lift dahlia-type tubers or tender crowns after the first light frost blackens the foliage and store them somewhere cool but frost-free.