Cold hardiness & minimum temperature

Is Endres's Bladderwort (Utricularia endresii)cold hardy? Hardiness zone & min temp

Also called Endres's bladderwort.

More about endres's bladderwort

About Endres's Bladderwort

Utricularia endresii · also called Endres's bladderwort · tropical

Utricularia endresii is a medium-sized epiphytic bladderwort native to highland cloud forests from Costa Rica and Panama through Colombia and Ecuador, typically found growing in wet moss, bark, or the leaf-axils of bromeliads in misty montane forests. It produces attractive lilac-to-violet flowers on slender scapes and its bladder traps capture microscopic soil organisms. The most important care fact is substrate: grow in pure long-fibre sphagnum moss kept continuously moist but never waterlogged, in a cool, humid environment that mimics cloud forest conditions. Utricularia is not listed on the ASPCA toxic plant database; classified as mildly-toxic as a precaution because no formal safety data exists.

Cold limit: USDA 10-12 (indoor in most climates) · RHS H1b (10–25°C)

Watch for — Failure to flower without a cool rest period: U. endresii benefits from a cool winter rest (10–15°C nights) to trigger flower bud initiation. Keeping it too warm year-round results in vegetative growth only with no blooms.

What endres's bladderwort's hardiness rating actually means

Endres's 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 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). Endres's Bladderwort has no frost tolerance at all — it is an indoor plant in any climate with a real winter.

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

Endres's Bladderwort hardiness — frequently asked questions

Is endres's bladderwort cold hardy?

Endres's 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. Endres's 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 endres's bladderwort can survive?

What hardiness zone is endres's bladderwort?

Endres's Bladderwort 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 endres's bladderwort 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 endres's bladderwort 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.