Cold hardiness & minimum temperature

Is Purple Bladderwort (Utricularia purpurea)cold hardy? Hardiness zone & min temp

Also called Eastern Purple Bladderwort, Purple Floating Bladderwort.

More about purple bladderwort

About Purple Bladderwort

Utricularia purpurea · also called Eastern Purple Bladderwort, Purple Floating Bladderwort · tropical

Utricularia purpurea is an aquatic carnivorous bladderwort native to eastern North America, growing as a free-floating or lightly anchored aquatic plant with tiny vacuum-trap bladders that capture zooplankton. It produces attractive small purple flowers. Requires still or slow-moving acidic water. Not toxic to pets.

Cold limit: USDA 5-11 (dormant tuber in cold climates) · RHS H5 (10-28°C)

Watch for — Poor flowering: Insufficient light is the primary cause. Provide at least 8 hours of bright light and ensure water is not too cold.

What purple bladderwort's hardiness rating actually means

Yes — purple bladderwort is genuinely cold hardy. Rated RHS H5 and USDA 5-11 (dormant tuber in cold climates), it lives outdoors all year and needs winter cold rather than protection from it. Its RHS rating of H5 means: Hardy in most of the UK and in cold winters. On the US scale that maps to USDA 5-11 (dormant tuber in cold 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 −15 to −10 °C. Purple Bladderwort is built for winter — once established it takes hard frost and snow in its stride.

Concretely, for purple bladderwort as it gets too cold:

It tolerates winter lows to about −15 to −10 °C once established.
Below its rated zone, the visible damage is browned or blackened top growth and, in the worst case, a killed crown or root.
First-year, newly planted, or container-grown specimens are noticeably less hardy than established garden plants — the roots are exposed.

Can purple bladderwort go outside or overwinter — and where?

Plant it out within USDA 5-11 (dormant tuber in cold climates) and it overwinters with little or no help.
It does not want to come indoors — a warm winter room actually weakens a hardy plant by denying it dormancy.
The real risks in its range are waterlogging, wind-rock on young plants, and a late hard frost on new growth — not ordinary winter cold.

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 purple bladderwort can be outside. US growers can check USDA zones; UK growers should use the RHS hardiness ratings, which match the H5 figure above.

Purple Bladderwort hardiness — frequently asked questions

Is purple bladderwort cold hardy?

Yes — purple bladderwort is genuinely cold hardy. Rated RHS H5 and USDA 5-11 (dormant tuber in cold climates), it lives outdoors all year and needs winter cold rather than protection from it. An outdoor plant. Purple Bladderwort is hardy across USDA 5-11 (dormant tuber in cold climates); it belongs in the ground or a frost-proof container, not on a windowsill, and many types actively need a cold winter to perform.

What is the minimum temperature purple bladderwort can survive?

Minimum survivable temperature is roughly about −15 to −10 °C. Purple Bladderwort is built for winter — once established it takes hard frost and snow in its stride.

What hardiness zone is purple bladderwort?

Purple Bladderwort is rated USDA 5-11 (dormant tuber in cold climates) and RHS H5 — Hardy in most of the UK and in cold winters.

Can purple bladderwort survive winter outside?

Plant it out within USDA 5-11 (dormant tuber in cold climates) and it overwinters with little or no help. It does not want to come indoors — a warm winter room actually weakens a hardy plant by denying it dormancy. The real risks in its range are waterlogging, wind-rock on young plants, and a late hard frost on new growth — not ordinary winter cold.

What happens to purple bladderwort below its minimum temperature?

It tolerates winter lows to about −15 to −10 °C once established. Below its rated zone, the visible damage is browned or blackened top growth and, in the worst case, a killed crown or root. First-year, newly planted, or container-grown specimens are noticeably less hardy than established garden plants — the roots are exposed.