Cold hardiness & minimum temperature

Is Hairy Bladderwort (Utricularia pubescens)cold hardy? Hardiness zone & min temp

Also called Hairy bladderwort.

More about hairy bladderwort

About Hairy Bladderwort

Utricularia pubescens · also called Hairy bladderwort · tropical

Utricularia pubescens is a terrestrial bladderwort with a remarkably wide pantropical distribution, found in India, Africa, and Central and South America, where it grows on constantly wet, often slightly rocky substrates and wet sandy soils with very low nutrient content. The name 'pubescens' (hairy in Latin) refers to fine trichomes present on the leaves. It is a small-growing species that thrives in a consistently wet, nutrient-poor, acidic medium and rewards growers with violet flowers on slender scapes. Utricularia is not listed in the ASPCA database; classified as mildly-toxic as a precaution.

Cold limit: USDA 10-12 (indoor in most climates) · RHS H1a (18–32°C)

What hairy bladderwort's hardiness rating actually means

Hairy Bladderwort 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 H1a means: Tropical — needs a heated room or greenhouse; no frost tolerance whatsoever. 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 above about 15 °C (warm, never cold). Hairy Bladderwort has no frost tolerance at all — it is an indoor plant in any climate with a real winter.

Concretely, for hairy bladderwort as it gets too cold:

Below about above about 15 °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 hairy bladderwort go outside or overwinter — and where?

It can holiday outdoors in summer once nights are reliably above above 15 °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 hairy bladderwort can be outside. US growers can check USDA zones; UK growers should use the RHS hardiness ratings, which match the H1a figure above.

Hairy Bladderwort hardiness — frequently asked questions

Is hairy bladderwort cold hardy?

Hairy Bladderwort 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. Hairy Bladderwort 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 hairy bladderwort can survive?

Minimum survivable temperature is roughly above about 15 °C (warm, never cold). Hairy Bladderwort has no frost tolerance at all — it is an indoor plant in any climate with a real winter.

What hardiness zone is hairy bladderwort?

Hairy Bladderwort is rated USDA 10-12 (indoor in most climates) and RHS H1a — Tropical — needs a heated room or greenhouse; no frost tolerance whatsoever.

Can hairy bladderwort survive winter outside?

It can holiday outdoors in summer once nights are reliably above above 15 °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 hairy bladderwort below its minimum temperature?

Below about above about 15 °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.