Cold hardiness & minimum temperature

Is Goldfish Plant (Nematanthus gregarius)cold hardy? Hardiness zone & min temp

Also called Goldfish plant, Clog plant, Candy corn plant, Guppy plant.

More about goldfish plant

About Goldfish Plant

Nematanthus gregarius · also called Goldfish plant, Clog plant · flowering

The goldfish plant is a trailing Brazilian gesneriad grown for the glossy, fleshy leaves and pouched orange flowers that look like tiny leaping goldfish. Its one defining need is bright but filtered light: too little and it sulks without blooming, while harsh direct sun scorches the waxy foliage. Treat it as a warm, humidity-loving houseplant.

Cold limit: USDA 10b-11b (per NC State Extension; grown outdoors only in frost-free subtropical/tropical areas, otherwise a houseplant) · RHS H1B (RHS) - needs heated greenhouse, conservatory or indoor conditions; can stand outside only in warm summer (10-15°C minimum) (18-27°C)

Watch for — Leaf drop: Sudden leaf shedding usually follows cold draughts, temperatures below about 10°C, or erratic watering. Keep it away from cold windows and heating vents and maintain steady moisture and warmth to stop the stress response.

What goldfish plant's hardiness rating actually means

Goldfish Plant 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 10b-11b (per NC State Extension; grown outdoors only in frost-free subtropical/tropical areas, otherwise a houseplant) — 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). Goldfish Plant has no frost tolerance at all — it is an indoor plant in any climate with a real winter.

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

Goldfish Plant hardiness — frequently asked questions

Is goldfish plant cold hardy?

Goldfish Plant 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. Goldfish Plant can only live outside year-round in genuinely frost-free climates (roughly USDA 10b-11b (per NC State Extension; grown outdoors only in frost-free subtropical/tropical areas, otherwise a houseplant)); everywhere else it is a houseplant that summers out at most.

What is the minimum temperature goldfish plant can survive?

What hardiness zone is goldfish plant?

Goldfish Plant is rated USDA 10b-11b (per NC State Extension; grown outdoors only in frost-free subtropical/tropical areas, otherwise a houseplant) and RHS H1b — Sub-tropical — a normal warm home is fine, but it cannot go outside in a cool season.

Can goldfish plant 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 goldfish plant 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.