Cold hardiness & minimum temperature

Is Cistus-Flowered Sundew (Drosera cistiflora)cold hardy? Hardiness zone & min temp

Also called cistus-flowered sundew.

More about cistus-flowered sundew

About Cistus-Flowered Sundew

Drosera cistiflora · also called cistus-flowered sundew · houseplant

Drosera cistiflora is a spectacular tuberous sundew from South Africa's Western Cape, prized for its unusually large, showy flowers — typically deep red, pink, or white — that rival a rockrose in size. It follows a Mediterranean-type seasonal cycle: active in the cool, wet winter and dormant as a tuber through the hot, dry summer.

Cold limit: USDA 9–10 · RHS H2 (5–22°C (active growth); 25–35°C (dormant tuber))

Watch for — Failure to flower: Insufficient winter sunlight is the main cause. Ensure the plant receives at least 6 hours of direct sun. The plant also needs a cool growing season (below 20°C); warm indoor temperatures prevent bud formation.

What cistus-flowered sundew's hardiness rating actually means

Cistus-Flowered Sundew 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 9–10 — 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 1 to 5 °C — tolerates cold but no real frost. Cistus-Flowered Sundew shrugs off cold nights but a real, sustained freeze will kill it.

Concretely, for cistus-flowered sundew 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 cistus-flowered sundew go outside or overwinter — and where?

It can live outside year-round only in the mildest, most sheltered part of USDA 9–10 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 cistus-flowered sundew 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 cistus-flowered sundew

Cistus-Flowered Sundew 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.

Cistus-Flowered Sundew hardiness — frequently asked questions

Is cistus-flowered sundew cold hardy?

Cistus-Flowered Sundew 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 9–10 (and sheltered UK gardens) cistus-flowered sundew can stay out; in colder areas it must be lifted, brought in, or treated as a frost-tender plant.

What is the minimum temperature cistus-flowered sundew can survive?

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

What hardiness zone is cistus-flowered sundew?

Cistus-Flowered Sundew is rated USDA 9–10 and RHS H2 — Tender — survives a frost-free greenhouse or a very mild, sheltered spot.

Can cistus-flowered sundew survive winter outside?

It can live outside year-round only in the mildest, most sheltered part of USDA 9–10 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 cistus-flowered sundew 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.