Cold hardiness & minimum temperature

Is Red Iochroma (Iochroma fuchsioides)cold hardy? Hardiness zone & min temp

Also called Red Iochroma, Scarlet Iochroma, Fuchsia-flowered Iochroma.

More about red iochroma

About Red Iochroma

Iochroma fuchsioides · also called Red Iochroma, Scarlet Iochroma · tropical

Iochroma fuchsioides is a Colombian and Ecuadorian cloud-forest shrub bearing cascading clusters of narrow, brilliant scarlet to orange-red tubular flowers that attract hummingbirds. It blooms in waves through the warmer months, is fast-growing and responds well to pruning. A striking conservatory specimen where temperatures stay above 10°C. All parts contain alkaloids and are toxic.

Cold limit: USDA 10-12 · RHS H1c (12-28°C)

Watch for — Bud drop: Moving the plant during bud development, low humidity, temperature fluctuations, or draughts frequently causes developing flower buds to abort. Choose a stable, draught-free position with 60%+ humidity and avoid repositioning once buds appear.

What red iochroma's hardiness rating actually means

Red Iochroma 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 10-12 — 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 about 5 °C (and never frost). Red Iochroma has no frost tolerance at all — it is an indoor plant in any climate with a real winter.

Concretely, for red iochroma 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 red iochroma 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 red iochroma can be outside. US growers can check USDA zones; UK growers should use the RHS hardiness ratings, which match the H1c figure above.

Red Iochroma hardiness — frequently asked questions

Is red iochroma cold hardy?

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

What is the minimum temperature red iochroma can survive?

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

What hardiness zone is red iochroma?

Red Iochroma is rated USDA 10-12 and RHS H1c — Warm-temperate — can summer outdoors but must come in well before the first frost.

Can red iochroma 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 red iochroma 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.