Cold hardiness & minimum temperature

Is Scarlet Drymonia (Drymonia coccinea)cold hardy? Hardiness zone & min temp

Also called scarlet drymonia.

More about scarlet drymonia

About Scarlet Drymonia

Drymonia coccinea · also called scarlet drymonia · tropical

Drymonia coccinea is a trailing or scandent gesneriad native to humid tropical forests of Central and South America. Its rich scarlet tubular flowers glow against deep-green, slightly corrugated foliage. It performs best in warm, high-humidity environments and is well-suited to hanging baskets or trained up a support in a bright, humid room.

Cold limit: USDA 11–12 · RHS H1a (18–26°C)

Watch for — Bud drop: Caused by sudden changes in temperature, humidity, or light. Avoid moving the plant while buds are forming, keep humidity above 65%, and protect from cold draughts.

What scarlet drymonia's hardiness rating actually means

Scarlet Drymonia 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 H1a means: Tropical — needs a heated room or greenhouse; no frost tolerance whatsoever. On the US scale that maps to USDA 11–12 — 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 above about 15 °C (warm, never cold). Scarlet Drymonia has no frost tolerance at all — it is an indoor plant in any climate with a real winter.

Concretely, for scarlet drymonia as it gets too cold:

Below about above about 15 °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 scarlet drymonia go outside or overwinter — and where?

It can holiday outdoors in summer once nights are reliably above above 15 °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 scarlet drymonia can be outside. US growers can check USDA zones; UK growers should use the RHS hardiness ratings, which match the H1a figure above.

Scarlet Drymonia hardiness — frequently asked questions

Is scarlet drymonia cold hardy?

Scarlet Drymonia 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. Scarlet Drymonia can only live outside year-round in genuinely frost-free climates (roughly USDA 11–12); everywhere else it is a houseplant that summers out at most.

What is the minimum temperature scarlet drymonia can survive?

Minimum survivable temperature is roughly above about 15 °C (warm, never cold). Scarlet Drymonia has no frost tolerance at all — it is an indoor plant in any climate with a real winter.

What hardiness zone is scarlet drymonia?

Scarlet Drymonia is rated USDA 11–12 and RHS H1a — Tropical — needs a heated room or greenhouse; no frost tolerance whatsoever.

Can scarlet drymonia survive winter outside?

It can holiday outdoors in summer once nights are reliably above above 15 °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 scarlet drymonia below its minimum temperature?

Below about above about 15 °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.