Cold hardiness & minimum temperature

Is Pontederia cordata 'Alba' (Pontederia cordata 'Alba')cold hardy? Hardiness zone & min temp

Also called White Pickerelweed.

More about pontederia cordata 'alba'

About Pontederia cordata 'Alba'

Pontederia cordata 'Alba' · also called White Pickerelweed · flowering

A white-flowered selection of native pickerelweed, bearing dense spikes of pure white blooms over glossy heart-shaped leaves all summer above shallow water. Loved by pollinators, it suits pond margins and bog gardens in full sun and spreads by rhizomes. Not individually ASPCA-listed, so treat with caution around pets despite the species' edible reputation.

Cold limit: USDA 3-10 · RHS H5 (-23 to 32°C)

What pontederia cordata 'alba''s hardiness rating actually means

Yes — pontederia cordata 'alba' is genuinely cold hardy. Rated RHS H5 and USDA 3-10, 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 3-10 — 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. Pontederia cordata 'Alba' is built for winter — once established it takes hard frost and snow in its stride.

Concretely, for pontederia cordata 'alba' 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 pontederia cordata 'alba' go outside or overwinter — and where?

Plant it out within USDA 3-10 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 pontederia cordata 'alba' can be outside. US growers can check USDA zones; UK growers should use the RHS hardiness ratings, which match the H5 figure above.

Pontederia cordata 'Alba' hardiness — frequently asked questions

Is pontederia cordata 'alba' cold hardy?

Yes — pontederia cordata 'alba' is genuinely cold hardy. Rated RHS H5 and USDA 3-10, it lives outdoors all year and needs winter cold rather than protection from it. An outdoor plant. Pontederia cordata 'Alba' is hardy across USDA 3-10; 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 pontederia cordata 'alba' can survive?

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

What hardiness zone is pontederia cordata 'alba'?

Pontederia cordata 'Alba' is rated USDA 3-10 and RHS H5 — Hardy in most of the UK and in cold winters.

Can pontederia cordata 'alba' survive winter outside?

Plant it out within USDA 3-10 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 pontederia cordata 'alba' 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.