Cold hardiness & minimum temperature

Is Red Indian Water Lily (Nymphaea rubra)cold hardy? Hardiness zone & min temp

Also called Red Indian Water Lily, Red Water Lily, Indian Red Lotus.

More about red indian water lily

About Red Indian Water Lily

Nymphaea rubra · also called Red Indian Water Lily, Red Water Lily · tropical

The Red Indian Water Lily is a striking tropical water lily native to India and Bangladesh, producing deep ruby-red to pink flowers up to 25 cm across and large reddish-green floating leaves. A night-blooming species, it opens its flowers from dusk through morning. Vigorous and fast-growing in warm, sunny outdoor ponds. Mildly toxic if ingested.

Cold limit: USDA 9-12 (outdoor ponds in warm climates; lift and store rhizomes above 15°C in winter in cooler zones) · RHS H1b (24-32°C)

Watch for — Flowers not opening at night: Water temperature below 22°C or inadequate nutrition; warm the pond area and apply fertiliser tablets.

What red indian water lily's hardiness rating actually means

Red Indian Water Lily 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 9-12 (outdoor ponds in warm climates; lift and store rhizomes above 15°C in winter in cooler zones) — 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). Red Indian Water Lily has no frost tolerance at all — it is an indoor plant in any climate with a real winter.

Concretely, for red indian water lily 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 red indian water lily 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 red indian water lily can be outside. US growers can check USDA zones; UK growers should use the RHS hardiness ratings, which match the H1b figure above.

Red Indian Water Lily hardiness — frequently asked questions

Is red indian water lily cold hardy?

Red Indian Water Lily 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. Red Indian Water Lily can only live outside year-round in genuinely frost-free climates (roughly USDA 9-12 (outdoor ponds in warm climates; lift and store rhizomes above 15°C in winter in cooler zones)); everywhere else it is a houseplant that summers out at most.

What is the minimum temperature red indian water lily can survive?

What hardiness zone is red indian water lily?

Red Indian Water Lily is rated USDA 9-12 (outdoor ponds in warm climates; lift and store rhizomes above 15°C in winter in cooler zones) and RHS H1b — Sub-tropical — a normal warm home is fine, but it cannot go outside in a cool season.

Can red indian water lily 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 red indian water lily 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.