Cold hardiness & minimum temperature

Is Round-leaved Sage (Salvia subrotunda)cold hardy? Hardiness zone & min temp

Also called Round-leaved sage, Giant Brazilian sage.

More about round-leaved sage

About Round-leaved Sage

Salvia subrotunda · also called Round-leaved sage, Giant Brazilian sage · flowering

Salvia subrotunda is a giant, heat-loving perennial sage native to the subtropical forests near the Iguazu Falls region on the Brazil–Argentina border, where it grows in rich, sheltered conditions. It can exceed 2.4 m in height by midsummer and produces abundant red-orange, trumpet-shaped flowers from mid-spring until the first frosts, making it exceptionally ornamental and highly attractive to hummingbirds and bees. It thrives with morning sun and afternoon shade in hot climates, and requires reliably moist, fertile soil. The ASPCA lists Salvia as non-toxic to cats and dogs.

Cold limit: USDA 8-10 · RHS H3 (5–35 °C)

What round-leaved sage's hardiness rating actually means

Round-leaved 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. Round-leaved Sage shrugs off cold nights but a real, sustained freeze will kill it.

Concretely, for round-leaved 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 round-leaved 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 round-leaved 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 round-leaved sage

Round-leaved 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.

Round-leaved Sage hardiness — frequently asked questions

Is round-leaved sage cold hardy?

Round-leaved 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) round-leaved 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 round-leaved sage can survive?

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

What hardiness zone is round-leaved sage?

Round-leaved 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 round-leaved 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 round-leaved 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.