Cold hardiness & minimum temperature

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

Also called Common Goldfish Plant, Goldfish Plant, Candy Corn Plant.

More about common goldfish plant

About Common Goldfish Plant

Nematanthus gregarius · also called Common Goldfish Plant, Goldfish Plant · tropical

Nematanthus gregarius is the most widely cultivated species of the goldfish plant group, native to the coastal Atlantic Forest of Brazil, where it grows epiphytically on tree branches. It bears masses of small, orange pouch-shaped flowers that strongly resemble leaping goldfish, produced prolifically from spring through autumn against a backdrop of glossy, dark-green oval leaves. The key care rule is maintaining consistent warmth — temperatures below 13 °C cause sudden leaf drop and can kill the plant. The ASPCA lists Nematanthus spp. as non-toxic to cats and dogs.

Cold limit: USDA 10-12 (indoor in most climates) · RHS H1b (16–24 °C)

Watch for — Sudden leaf drop: Caused by cold draughts, temperatures below 13 °C, or a dramatic temperature swing; keep plants away from exterior doors and cold windowsills in winter.

What common goldfish plant's hardiness rating actually means

Common 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 10-12 (indoor in most climates) — 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). Common Goldfish Plant has no frost tolerance at all — it is an indoor plant in any climate with a real winter.

Concretely, for common 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 common 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 common 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.

Common Goldfish Plant hardiness — frequently asked questions

Is common goldfish plant cold hardy?

Common 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. Common Goldfish Plant can only live outside year-round in genuinely frost-free climates (roughly USDA 10-12 (indoor in most climates)); everywhere else it is a houseplant that summers out at most.

What is the minimum temperature common goldfish plant can survive?

What hardiness zone is common goldfish plant?

Common Goldfish Plant is rated USDA 10-12 (indoor in most climates) and RHS H1b — Sub-tropical — a normal warm home is fine, but it cannot go outside in a cool season.

Can common 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 common 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.