Cold hardiness & minimum temperature

Is Petiole Sundew (Drosera petiolaris)cold hardy? Hardiness zone & min temp

Also called Petiole sundew, Woolly sundew.

More about petiole sundew

About Petiole Sundew

Drosera petiolaris · also called Petiole sundew, Woolly sundew · tropical

Drosera petiolaris is the type species of the petiolaris complex, native to seasonally flooded grasslands and floodplains across the Northern Territory and far north Queensland, Australia. It is a warm-tropical carnivorous plant adapted to a strongly seasonal monsoon climate — requiring a hot, wet growing season followed by a distinctly drier, still-warm rest period. The single most important care fact is that it absolutely cannot tolerate cold: temperatures below 15 °C will cause dormancy failure and death. Drosera is not listed as toxic to cats or dogs by the ASPCA and is considered non-toxic to pets.

Cold limit: USDA 10-12 (indoor in most climates) · RHS H1b (20–40 °C (growing); 18–28 °C (rest))

Watch for — Premature dormancy in summer: If temperatures drop below 20 °C or day length shortens significantly, the plant sheds leaves and enters dormancy unseasonally. Keep temperatures consistently warm (above 22 °C) and maintain long photoperiods during the intended growing season.

What petiole sundew's hardiness rating actually means

Petiole 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 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). Petiole Sundew has no frost tolerance at all — it is an indoor plant in any climate with a real winter.

Concretely, for petiole sundew 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 petiole sundew 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 petiole sundew can be outside. US growers can check USDA zones; UK growers should use the RHS hardiness ratings, which match the H1b figure above.

Petiole Sundew hardiness — frequently asked questions

Is petiole sundew cold hardy?

Petiole 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. Petiole Sundew 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 petiole sundew can survive?

What hardiness zone is petiole sundew?

Petiole Sundew 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 petiole sundew 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 petiole sundew 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.