Cold hardiness & minimum temperature

Is Nymphoides indica (Nymphoides indica)cold hardy? Hardiness zone & min temp

Also called Water Snowflake, Indian Floating Heart.

More about nymphoides indica

About Nymphoides indica

Nymphoides indica · also called Water Snowflake, Indian Floating Heart · tropical

Water snowflake is a tender tropical aquatic prized for its delicate, fringed white flowers that look dusted with frost, held above round floating leaves. It roots in warm pond mud and flowers continuously in heat. Unlike its hardy yellow cousin it is frost-sensitive, so overwinter it indoors or treat as an annual in cool climates.

Cold limit: USDA 9-11 (tender; overwinter frost-free) · RHS H1c (20-30°C)

Watch for — Cold damage: Collapses below about 10°C and is killed by frost. Lift the basket into a frost-free aquarium or tub over winter in temperate gardens.

What nymphoides indica's hardiness rating actually means

Nymphoides indica 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 H1c means: Warm-temperate — can summer outdoors but must come in well before the first frost. On the US scale that maps to USDA 9-11 (tender; overwinter frost-free) — 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 5 °C (and never frost). Nymphoides indica has no frost tolerance at all — it is an indoor plant in any climate with a real winter.

Concretely, for nymphoides indica as it gets too cold:

Below about about 5 °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 nymphoides indica go outside or overwinter — and where?

It can holiday outdoors in summer once nights are reliably above 5 °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 nymphoides indica can be outside. US growers can check USDA zones; UK growers should use the RHS hardiness ratings, which match the H1c figure above.

Nymphoides indica hardiness — frequently asked questions

Is nymphoides indica cold hardy?

Nymphoides indica 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. Nymphoides indica can only live outside year-round in genuinely frost-free climates (roughly USDA 9-11 (tender; overwinter frost-free)); everywhere else it is a houseplant that summers out at most.

What is the minimum temperature nymphoides indica can survive?

Minimum survivable temperature is roughly about 5 °C (and never frost). Nymphoides indica has no frost tolerance at all — it is an indoor plant in any climate with a real winter.

What hardiness zone is nymphoides indica?

Nymphoides indica is rated USDA 9-11 (tender; overwinter frost-free) and RHS H1c — Warm-temperate — can summer outdoors but must come in well before the first frost.

Can nymphoides indica survive winter outside?

It can holiday outdoors in summer once nights are reliably above 5 °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 nymphoides indica below its minimum temperature?

Below about about 5 °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.