Cold hardiness & minimum temperature

Is Painted Nettle (Plectranthus scutellarioides)cold hardy? Hardiness zone & min temp

Also called Painted Nettle, Coleus, Flame Nettle.

More about painted nettle

About Painted Nettle

Plectranthus scutellarioides · also called Painted Nettle, Coleus · tropical

Plectranthus scutellarioides (syn. Coleus scutellarioides) is a fast-growing tropical foliage plant from Southeast Asia and the Pacific, grown for its brilliantly coloured leaves in combinations of red, orange, yellow, pink, purple, and green. It thrives in bright, indirect light and consistently moist, well-drained compost, and grows rapidly in warmth and humidity. Pinching out flower spikes as soon as they appear prolongs the vivid leaf colour and prevents premature decline. Toxic to cats, dogs, and horses.

Cold limit: USDA 10-12 (indoor in most climates) · RHS H1b (15–30°C)

What painted nettle's hardiness rating actually means

Painted Nettle 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). Painted Nettle has no frost tolerance at all — it is an indoor plant in any climate with a real winter.

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

Painted Nettle hardiness — frequently asked questions

Is painted nettle cold hardy?

Painted Nettle 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. Painted Nettle 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 painted nettle can survive?

What hardiness zone is painted nettle?

Painted Nettle 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 painted nettle 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 painted nettle 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.