Cold hardiness & minimum temperature

Is Cape Sundew (Drosera capensis)cold hardy? Hardiness zone & min temp

Also called Cape sundew, Cape rainbow plant.

More about cape sundew

About Cape Sundew

Drosera capensis · also called Cape sundew, Cape rainbow plant · houseplant

Drosera capensis is a subtropical carnivorous perennial native to the Cape region of South Africa, where it grows in open, nutrient-poor, moist peaty ground in full sun. It is one of the easiest carnivorous plants to grow, producing rosettes of strap-shaped leaves densely studded with red, gland-tipped tentacles that trap, curl around, and digest small insects. The key rule is to use only mineral-free water (rainwater, distilled, or reverse-osmosis) — tap water mineral build-up will kill it within months. Non-toxic to pets according to carnivorous plant specialist authorities; the ASPCA has not individually listed the species, so 'mildly-toxic' is applied as a precautionary classification.

Cold limit: USDA 9-11 · RHS H1c (5–32°C (optimal 15–28°C))

What cape sundew's hardiness rating actually means

Cape Sundew 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 H1c means: Warm-temperate — can summer outdoors but must come in well before the first frost. 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 5 °C (and never frost). Cape Sundew has no frost tolerance at all — it is an indoor plant in any climate with a real winter.

Concretely, for cape sundew as it gets too cold:

Below about about 5 °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 cape sundew go outside or overwinter — and where?

It can holiday outdoors in summer once nights are reliably above 5 °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 cape sundew can be outside. US growers can check USDA zones; UK growers should use the RHS hardiness ratings, which match the H1c figure above.

Cape Sundew hardiness — frequently asked questions

Is cape sundew cold hardy?

Cape Sundew 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. Cape Sundew can only live outside year-round in genuinely frost-free climates (roughly USDA 9-11); everywhere else it is a houseplant that summers out at most.

What is the minimum temperature cape sundew can survive?

Minimum survivable temperature is roughly about 5 °C (and never frost). Cape Sundew has no frost tolerance at all — it is an indoor plant in any climate with a real winter.

What hardiness zone is cape sundew?

Cape Sundew is rated USDA 9-11 and RHS H1c — Warm-temperate — can summer outdoors but must come in well before the first frost.

Can cape sundew survive winter outside?

It can holiday outdoors in summer once nights are reliably above 5 °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 cape sundew below its minimum temperature?

Below about about 5 °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.