Cold hardiness & minimum temperature

Is White-Budded Sundew (Drosera leucoblasta)cold hardy? Hardiness zone & min temp

Also called White-budded sundew, Pygmy sundew.

More about white-budded sundew

About White-Budded Sundew

Drosera leucoblasta · also called White-budded sundew, Pygmy sundew · houseplant

Drosera leucoblasta is a pygmy sundew endemic to south-western Western Australia, where it grows in clayey sand and laterite soils in open heathland from the Darling Scarp east through the Wheatbelt to Esperance. Its common name references the distinctive white stipular buds (leucos = white, blastos = bud) at the centre of the rosette. The most important care fact is that it requires mineral-poor, very well-draining soil and pure, low-mineral water — tap water will kill it. It is not listed on the ASPCA toxic plant database and is considered mildly-toxic by precaution, though no serious toxicity to pets is reported.

Cold limit: USDA 9-11 (indoor in cooler climates) · RHS H2 (5-30°C)

Watch for — Rotting crown: Caused by standing water pooling in the rosette centre or excessive heat. Improve air circulation, keep water in the tray rather than overhead, and ensure temperatures stay below 32°C during summer.

What white-budded sundew's hardiness rating actually means

White-Budded 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 9-11 (indoor in cooler 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 1 to 5 °C — tolerates cold but no real frost. White-Budded Sundew shrugs off cold nights but a real, sustained freeze will kill it.

Concretely, for white-budded 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 white-budded sundew go outside or overwinter — and where?

It can live outside year-round only in the mildest, most sheltered part of USDA 9-11 (indoor in cooler climates) 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 white-budded 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 white-budded sundew

White-Budded 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.

White-Budded Sundew hardiness — frequently asked questions

Is white-budded sundew cold hardy?

White-Budded 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 9-11 (indoor in cooler climates) (and sheltered UK gardens) white-budded 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 white-budded sundew can survive?

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

What hardiness zone is white-budded sundew?

White-Budded Sundew is rated USDA 9-11 (indoor in cooler climates) and RHS H2 — Tender — survives a frost-free greenhouse or a very mild, sheltered spot.

Can white-budded sundew survive winter outside?

It can live outside year-round only in the mildest, most sheltered part of USDA 9-11 (indoor in cooler climates) 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 white-budded 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.