Cold hardiness & minimum temperature

Is Plectranthus scutellarioides 'Black Dragon' (Plectranthus scutellarioides 'Black Dragon')cold hardy? Hardiness zone & min temp

Also called Black Dragon Coleus, Dark Coleus.

More about plectranthus scutellarioides 'black dragon'

About Plectranthus scutellarioides 'Black Dragon'

Plectranthus scutellarioides 'Black Dragon' · also called Black Dragon Coleus, Dark Coleus · flowering

'Black Dragon' is a compact coleus prized for deeply ruffled, near-black burgundy foliage rather than its small blue flower spikes. Grown as a tender annual in beds or containers, it thrives in part shade with rich moist soil and pinches into a dense mound. Strong colour develops in bright, filtered light through the warm season.

Cold limit: USDA 10-11 (grown as a frost-tender annual elsewhere) · RHS H1c (18-29°C)

What plectranthus scutellarioides 'black dragon''s hardiness rating actually means

Plectranthus scutellarioides 'Black Dragon' 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 10-11 (grown as a frost-tender annual elsewhere) — 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). Plectranthus scutellarioides 'Black Dragon' has no frost tolerance at all — it is an indoor plant in any climate with a real winter.

Concretely, for plectranthus scutellarioides 'black dragon' 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 plectranthus scutellarioides 'black dragon' 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 plectranthus scutellarioides 'black dragon' can be outside. US growers can check USDA zones; UK growers should use the RHS hardiness ratings, which match the H1c figure above.

Plectranthus scutellarioides 'Black Dragon' hardiness — frequently asked questions

Is plectranthus scutellarioides 'black dragon' cold hardy?

Plectranthus scutellarioides 'Black Dragon' 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. Plectranthus scutellarioides 'Black Dragon' can only live outside year-round in genuinely frost-free climates (roughly USDA 10-11 (grown as a frost-tender annual elsewhere)); everywhere else it is a houseplant that summers out at most.

What is the minimum temperature plectranthus scutellarioides 'black dragon' can survive?

What hardiness zone is plectranthus scutellarioides 'black dragon'?

Plectranthus scutellarioides 'Black Dragon' is rated USDA 10-11 (grown as a frost-tender annual elsewhere) and RHS H1c — Warm-temperate — can summer outdoors but must come in well before the first frost.

Can plectranthus scutellarioides 'black dragon' 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 plectranthus scutellarioides 'black dragon' 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.