Cold hardiness & minimum temperature

Is Large-Leaved Butterwort (Pinguicula macrophylla)cold hardy? Hardiness zone & min temp

Also called Large-leaved butterwort, Mexican butterwort.

More about large-leaved butterwort

About Large-Leaved Butterwort

Pinguicula macrophylla · also called Large-leaved butterwort, Mexican butterwort · houseplant

Pinguicula macrophylla is an unusual carnivorous butterwort endemic to Guanajuato, Mexico, notable for its large oval carnivorous leaves borne on distinctive long petioles (leaf stalks) in summer — a feature that sets it apart from most other Mexican Pinguicula. In winter it retreats to a bulb-like dormant bud at the soil surface, and the critical care point is to allow the substrate to dry out significantly during this rest phase. It is not confirmed as non-toxic on the ASPCA database and carries a precautionary mildly-toxic rating.

Cold limit: USDA 10-12 (indoor in most climates) · RHS H1c (13-29°C)

Watch for — Bulb rot in winter dormancy: Overwatering during the dormant bulb phase is the primary cause of plant loss. Once the carnivorous leaves fully die back, reduce watering to once every 2-3 weeks and ensure the pot drains freely. Store the pot on its side if rot persists.

What large-leaved butterwort's hardiness rating actually means

Large-Leaved Butterwort 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 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 5 °C (and never frost). Large-Leaved Butterwort has no frost tolerance at all — it is an indoor plant in any climate with a real winter.

Concretely, for large-leaved butterwort 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 large-leaved butterwort 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 large-leaved butterwort can be outside. US growers can check USDA zones; UK growers should use the RHS hardiness ratings, which match the H1c figure above.

Large-Leaved Butterwort hardiness — frequently asked questions

Is large-leaved butterwort cold hardy?

Large-Leaved Butterwort 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. Large-Leaved Butterwort 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 large-leaved butterwort can survive?

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

What hardiness zone is large-leaved butterwort?

Large-Leaved Butterwort is rated USDA 10-12 (indoor in most climates) and RHS H1c — Warm-temperate — can summer outdoors but must come in well before the first frost.

Can large-leaved butterwort 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 large-leaved butterwort 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.