Cold hardiness & minimum temperature

Is Banded Cape Primrose (Streptocarpus fasciatus)cold hardy? Hardiness zone & min temp

Also called Banded Cape Primrose, Banded Streptocarpus.

More about banded cape primrose

About Banded Cape Primrose

Streptocarpus fasciatus · also called Banded Cape Primrose, Banded Streptocarpus · flowering

Streptocarpus fasciatus is a rosette-forming perennial from the moist, shaded rocky hillsides and afromontane forest margins of Mpumalanga Province in South Africa, distinguished by its strap-shaped leaves with attractive banded patterning. Like all Cape primroses, it produces a succession of tubular flowers on long, wiry stalks that arise directly from the leaf bases, typically blooming in purplish-violet tones. The single most important care rule is to avoid overwatering and never wet the leaves during watering, as the velvety foliage is very prone to fungal rot. The ASPCA lists Cape Primrose (Streptocarpus spp.) as non-toxic to cats, dogs, and horses.

Cold limit: USDA 10-12 (indoor in most climates) · RHS H1b (15-24°C)

What banded cape primrose's hardiness rating actually means

Banded Cape Primrose is not cold hardy. It is a tropical houseplant that dies if it is left out through frost — there is no zone where it overwinters outdoors in a UK or cold-US climate. Its RHS rating of H1b means: Sub-tropical — a normal warm home is fine, but it cannot go outside in a cool season. On the US scale that maps to USDA 10-12 (indoor in most climates) — 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 10 °C (sustained cold below this is damaging). Banded Cape Primrose has no frost tolerance at all — it is an indoor plant in any climate with a real winter.

Concretely, for banded cape primrose as it gets too cold:

Below about about 10 °C, growth stalls and the leaves start to show cold stress — dark, water-soaked, or yellowing patches.
A single light frost blackens the foliage; a hard freeze kills the whole plant, roots included, and it does not recover.
Even a cold, draughty windowsill or an unheated porch in winter can be enough to damage it permanently.

Can banded cape primrose go outside or overwinter — and where?

It can holiday outdoors in summer once nights are reliably above 10 °C, in shade or dappled light, hardened off gradually.
Bring it back indoors well before the first autumn frost — do not wait for a frost warning, move it when nights drop toward 10-12 °C.
It will never overwinter outside in a temperate climate; the indoors is its winter home, full stop.

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 banded cape primrose can be outside. US growers can check USDA zones; UK growers should use the RHS hardiness ratings, which match the H1b figure above.

Banded Cape Primrose hardiness — frequently asked questions

Is banded cape primrose cold hardy?

Banded Cape Primrose is not cold hardy. It is a tropical houseplant that dies if it is left out through frost — there is no zone where it overwinters outdoors in a UK or cold-US climate. Indoor-only in almost every home. Banded Cape Primrose can only live outside year-round in genuinely frost-free climates (roughly USDA 10-12 (indoor in most climates)); everywhere else it is a houseplant that summers out at most.

What is the minimum temperature banded cape primrose can survive?

What hardiness zone is banded cape primrose?

Banded Cape Primrose is rated USDA 10-12 (indoor in most climates) and RHS H1b — Sub-tropical — a normal warm home is fine, but it cannot go outside in a cool season.

Can banded cape primrose survive winter outside?

It can holiday outdoors in summer once nights are reliably above 10 °C, in shade or dappled light, hardened off gradually. Bring it back indoors well before the first autumn frost — do not wait for a frost warning, move it when nights drop toward 10-12 °C. It will never overwinter outside in a temperate climate; the indoors is its winter home, full stop.

What happens to banded cape primrose below its minimum temperature?

Below about about 10 °C, growth stalls and the leaves start to show cold stress — dark, water-soaked, or yellowing patches. A single light frost blackens the foliage; a hard freeze kills the whole plant, roots included, and it does not recover. Even a cold, draughty windowsill or an unheated porch in winter can be enough to damage it permanently.