Cold hardiness & minimum temperature

Is Catharanthus roseus 'Titan Polka Dot' (Catharanthus roseus 'Titan Polka Dot')cold hardy? Hardiness zone & min temp

Also called Titan Polka Dot Vinca, Bicolor Annual Vinca.

More about catharanthus roseus 'titan polka dot'

About Catharanthus roseus 'Titan Polka Dot'

Catharanthus roseus 'Titan Polka Dot' · also called Titan Polka Dot Vinca, Bicolor Annual Vinca · flowering

'Titan Polka Dot' is a large-flowered, upright annual vinca with white petals and a vivid rose-red eye, blooming non-stop through summer heat. Bred for vigour and a bushy, well-branched habit, it loves full sun and dry roots and flowers without deadheading. All parts contain vinca alkaloids and are toxic to cats and dogs if eaten.

Cold limit: USDA 10-11 (grown as a summer annual in cooler zones) · RHS H1c (20-32°C)

Watch for — Root and stem rot: Triggered by overwatering or cold, wet soil. Use free-draining medium and water only once the soil has dried out.

What catharanthus roseus 'titan polka dot''s hardiness rating actually means

Catharanthus roseus 'Titan Polka Dot' 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 summer annual in cooler zones) — 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). Catharanthus roseus 'Titan Polka Dot' has no frost tolerance at all — it is an indoor plant in any climate with a real winter.

Concretely, for catharanthus roseus 'titan polka dot' 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 catharanthus roseus 'titan polka dot' 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 catharanthus roseus 'titan polka dot' can be outside. US growers can check USDA zones; UK growers should use the RHS hardiness ratings, which match the H1c figure above.

Catharanthus roseus 'Titan Polka Dot' hardiness — frequently asked questions

Is catharanthus roseus 'titan polka dot' cold hardy?

Catharanthus roseus 'Titan Polka Dot' 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. Catharanthus roseus 'Titan Polka Dot' can only live outside year-round in genuinely frost-free climates (roughly USDA 10-11 (grown as a summer annual in cooler zones)); everywhere else it is a houseplant that summers out at most.

What is the minimum temperature catharanthus roseus 'titan polka dot' can survive?

What hardiness zone is catharanthus roseus 'titan polka dot'?

Catharanthus roseus 'Titan Polka Dot' is rated USDA 10-11 (grown as a summer annual in cooler zones) and RHS H1c — Warm-temperate — can summer outdoors but must come in well before the first frost.

Can catharanthus roseus 'titan polka dot' 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 catharanthus roseus 'titan polka dot' 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.