Cold hardiness & minimum temperature

Is Fritsch's Goldfish Plant (Nematanthus fritschii)cold hardy? Hardiness zone & min temp

Also called Fritsch's Goldfish Plant.

More about fritsch's goldfish plant

About Fritsch's Goldfish Plant

Nematanthus fritschii · also called Fritsch's Goldfish Plant · tropical

Nematanthus fritschii is a larger-growing epiphytic gesneriad from the Atlantic Forest of Brazil, notable for its relatively long, shiny leaves (up to 8 cm) with a distinctive red flush on the undersides that attracts hummingbird pollinators in the wild. It produces pink to rose-red, funnel-shaped, slightly fuzzy flowers suspended on arching stems, typically blooming in spring and early summer. This species grows more vigorously than compact Nematanthus and benefits from a hanging basket that allows its stems to arch freely. The ASPCA lists Nematanthus spp. as non-toxic to cats and dogs.

Cold limit: USDA 10-12 (indoor in most climates) · RHS H1b (15–25 °C)

Watch for — Leggy, non-blooming stems: Insufficient light is the primary cause; move the plant to a brighter position or provide supplemental grow lighting, and pinch stem tips in late winter to encourage branching and more flowering shoots.

What fritsch's goldfish plant's hardiness rating actually means

Fritsch's 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). Fritsch's Goldfish Plant has no frost tolerance at all — it is an indoor plant in any climate with a real winter.

Concretely, for fritsch's 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 fritsch's 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 fritsch's 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.

Fritsch's Goldfish Plant hardiness — frequently asked questions

Is fritsch's goldfish plant cold hardy?

Fritsch's 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. Fritsch's 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 fritsch's goldfish plant can survive?

What hardiness zone is fritsch's goldfish plant?

Fritsch's 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 fritsch's 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 fritsch's 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.