Cold hardiness & minimum temperature

Is Crimson Water Lily (Nymphaea 'Laydekeri Fulgens')cold hardy? Hardiness zone & min temp

Also called Crimson Water Lily, Fulgens Water Lily, Red Laydekeri.

More about crimson water lily

About Crimson Water Lily

Nymphaea 'Laydekeri Fulgens' · also called Crimson Water Lily, Fulgens Water Lily · flowering

One of the most richly coloured of all hardy water lilies, 'Laydekeri Fulgens' bears deep crimson-magenta flowers with contrasting orange-red stamens from June to September. A compact Laydeker hybrid suited to small to medium ponds, it is exceptionally hardy and free-flowering. Leaves emerge purple-blotched, maturing to plain green, adding seasonal foliage interest.

Cold limit: USDA 4–10 · RHS H7 (-15–35°C (active growth 15–28°C))

Watch for — Crown rot in cold waterlogged soil: In excessively cold, stagnant, or shallow ponds that freeze solid, the rhizome can rot over winter. In very shallow water features in zone 4–5, sink the basket to the deepest part of the pond before the first frost, or move indoors in a bucket of damp soil.

What crimson water lily's hardiness rating actually means

Yes — crimson water lily is genuinely cold hardy. Rated RHS H7 and USDA 4–10, it lives outdoors all year and needs winter cold rather than protection from it. Its RHS rating of H7 means: Hardy in the severest European continental winters. On the US scale that maps to USDA 4–10 — 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 below about −20 °C. Crimson Water Lily is built for winter — once established it takes hard frost and snow in its stride.

Concretely, for crimson water lily as it gets too cold:

It tolerates winter lows to about −20 °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 crimson water lily go outside or overwinter — and where?

Plant it out within USDA 4–10 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 crimson water lily can be outside. US growers can check USDA zones; UK growers should use the RHS hardiness ratings, which match the H7 figure above.

Crimson Water Lily hardiness — frequently asked questions

Is crimson water lily cold hardy?

Yes — crimson water lily is genuinely cold hardy. Rated RHS H7 and USDA 4–10, it lives outdoors all year and needs winter cold rather than protection from it. An outdoor plant. Crimson Water Lily is hardy across USDA 4–10; 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 crimson water lily can survive?

Minimum survivable temperature is roughly below about −20 °C. Crimson Water Lily is built for winter — once established it takes hard frost and snow in its stride.

What hardiness zone is crimson water lily?

Crimson Water Lily is rated USDA 4–10 and RHS H7 — Hardy in the severest European continental winters.

Can crimson water lily survive winter outside?

Plant it out within USDA 4–10 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 crimson water lily below its minimum temperature?

It tolerates winter lows to about −20 °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.