Cold hardiness & minimum temperature

Is Pelargonium 'Rollisson's Unique' (Pelargonium 'Rollisson's Unique')cold hardy? Hardiness zone & min temp

Also called Rollisson's Unique pelargonium, Unique geranium.

More about pelargonium 'rollisson's unique'

About Pelargonium 'Rollisson's Unique'

Pelargonium 'Rollisson's Unique' · also called Rollisson's Unique pelargonium, Unique geranium · flowering

An old Unique-group pelargonium forming a tall, shrubby plant with rough, aromatic cut foliage and abundant wine-red flowers feathered with darker veining. Vigorous and long-flowering, it suits large containers, conservatories and sunny borders. Like all pelargoniums it is frost-tender, demanding full sun, sharp drainage and frost-free overwintering to perform year after year.

Cold limit: USDA 9-11 (tender; overwinter under glass where frosts occur) · RHS H1c (10-24°C)

Watch for — Sparse flowering: Too little sun or no pruning leads to leafy, flower-shy plants. Give full sun and prune back in late winter to encourage flowering wood.

What pelargonium 'rollisson's unique''s hardiness rating actually means

Pelargonium 'Rollisson's Unique' 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 9-11 (tender; overwinter under glass where frosts occur) — 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). Pelargonium 'Rollisson's Unique' has no frost tolerance at all — it is an indoor plant in any climate with a real winter.

Concretely, for pelargonium 'rollisson's unique' 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 pelargonium 'rollisson's unique' 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 pelargonium 'rollisson's unique' can be outside. US growers can check USDA zones; UK growers should use the RHS hardiness ratings, which match the H1c figure above.

Pelargonium 'Rollisson's Unique' hardiness — frequently asked questions

Is pelargonium 'rollisson's unique' cold hardy?

Pelargonium 'Rollisson's Unique' 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. Pelargonium 'Rollisson's Unique' can only live outside year-round in genuinely frost-free climates (roughly USDA 9-11 (tender; overwinter under glass where frosts occur)); everywhere else it is a houseplant that summers out at most.

What is the minimum temperature pelargonium 'rollisson's unique' can survive?

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

What hardiness zone is pelargonium 'rollisson's unique'?

Pelargonium 'Rollisson's Unique' is rated USDA 9-11 (tender; overwinter under glass where frosts occur) and RHS H1c — Warm-temperate — can summer outdoors but must come in well before the first frost.

Can pelargonium 'rollisson's unique' 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 pelargonium 'rollisson's unique' 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.