Cold hardiness & minimum temperature

Is Mexican Butterwort (Pinguicula moranensis)cold hardy? Hardiness zone & min temp

Also called Mexican Butterwort, Butterwort, Ping, Pinguicula.

More about mexican butterwort

About Mexican Butterwort

Pinguicula moranensis · also called Mexican Butterwort, Butterwort · houseplant

Mexican butterwort is a carnivorous rosette plant whose sticky, gland-covered leaves trap fungus gnats and small flies. Give it bright light, a mineral (peat-and-sand) mix, and distilled or rainwater only — never tap. It is not on the ASPCA list either way, so treat it as mildly toxic and confirm with a vet.

Cold limit: USDA 9a-11b (15-27°C)

Watch for — Rot during winter dormancy: Keeping the plant as wet in winter as in summer rots the succulent resting rosette. Once it switches to the tight glandless winter form, reduce watering and keep the mix only barely damp.

What mexican butterwort's hardiness rating actually means

Mexican 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 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 9a-11b — 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). Mexican Butterwort has no frost tolerance at all — it is an indoor plant in any climate with a real winter.

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

Mexican Butterwort hardiness — frequently asked questions

Is mexican butterwort cold hardy?

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

What is the minimum temperature mexican butterwort can survive?

What hardiness zone is mexican butterwort?

Mexican Butterwort is rated USDA 9a-11b and RHS H1b — Sub-tropical — a normal warm home is fine, but it cannot go outside in a cool season.

Can mexican butterwort 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 mexican butterwort 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.