Cold hardiness & minimum temperature

Is Purple-flowered Sage (Salvia purpurea)cold hardy? Hardiness zone & min temp

Also called Purple-flowered Sage, Autumn Purple Sage.

More about purple-flowered sage

About Purple-flowered Sage

Salvia purpurea · also called Purple-flowered Sage, Autumn Purple Sage · flowering

Salvia purpurea is an evergreen shrubby sage native to southern Mexico and Guatemala, where it grows at moderate elevations in rich, well-drained soils with summer rainfall and mild winters. It bears numerous small but strikingly translucent light-purple flowers from summer through autumn, with yellowish-green fragrant foliage that brightens shaded garden areas better than many other salvias. It thrives in USDA zones 9–11, tolerating more shade than most members of the genus, and works well in containers in cooler climates where it can be overwintered frost-free. This species is not individually listed by the ASPCA; a precautionary mildly-toxic classification is applied.

Cold limit: USDA 9-11 · RHS H2 (5–35°C)

Watch for — Frost damage: Tender in frost; even light frosts (−2°C/28°F) can damage or kill the above-ground portions. In zones 8 or cooler, grow in containers and bring under glass before the first frost.

What purple-flowered sage's hardiness rating actually means

Purple-flowered Sage is half-hardy (RHS H2). 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 H2 means: Tender — survives a frost-free greenhouse or a very mild, sheltered spot. On the US scale that maps to USDA 9-11 — 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 1 to 5 °C — tolerates cold but no real frost. Purple-flowered Sage shrugs off cold nights but a real, sustained freeze will kill it.

Concretely, for purple-flowered sage as it gets too cold:

Down to roughly about 1 to 5 °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 purple-flowered sage go outside or overwinter — and where?

It can live outside year-round only in the mildest, most sheltered part of USDA 9-11 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 purple-flowered sage can be outside. US growers can check USDA zones; UK growers should use the RHS hardiness ratings, which match the H2 figure above.

Frost protection for borderline purple-flowered sage

Purple-flowered 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.

Purple-flowered Sage hardiness — frequently asked questions

Is purple-flowered sage cold hardy?

Purple-flowered Sage is half-hardy (RHS H2). 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 9-11 (and sheltered UK gardens) purple-flowered 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 purple-flowered sage can survive?

Minimum survivable temperature is roughly about 1 to 5 °C — tolerates cold but no real frost. Purple-flowered Sage shrugs off cold nights but a real, sustained freeze will kill it.

What hardiness zone is purple-flowered sage?

Purple-flowered Sage is rated USDA 9-11 and RHS H2 — Tender — survives a frost-free greenhouse or a very mild, sheltered spot.

Can purple-flowered sage survive winter outside?

It can live outside year-round only in the mildest, most sheltered part of USDA 9-11 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 purple-flowered 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.