Cold hardiness & minimum temperature

Is Ipomoea nil 'Scarlett O'Hara' (Ipomoea nil 'Scarlett O'Hara')cold hardy? Hardiness zone & min temp

Also called Scarlett O'Hara morning glory.

More about ipomoea nil 'scarlett o'hara'

About Ipomoea nil 'Scarlett O'Hara'

Ipomoea nil 'Scarlett O'Hara' · also called Scarlett O'Hara morning glory · flowering

'Scarlett O'Hara' is an award-winning Japanese morning glory (Ipomoea nil) cultivar with large, rich rosy-red to wine-crimson trumpet flowers and a paler throat, opening each morning through summer and autumn. A vigorous annual twiner grown easily from seed, it clothes trellises and arches quickly and flowers freely until cut down by the first frost.

Cold limit: USDA 2-11 (frost-tender warm-season annual) · RHS H2 (18 to 30°C)

Watch for — Frost sensitivity: Completely frost-tender. Do not sow out or plant until all danger of frost has passed and soil has warmed.

What ipomoea nil 'scarlett o'hara''s hardiness rating actually means

Ipomoea nil 'Scarlett O'Hara' is half-hardy (RHS H2). It survives a mild winter outdoors in a sheltered spot, but a hard frost kills it — so in colder zones it is lifted, potted, or grown as a tender plant. Its RHS rating of H2 means: Tender — survives a frost-free greenhouse or a very mild, sheltered spot. On the US scale that maps to USDA 2-11 (frost-tender warm-season annual) — 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 1 to 5 °C — tolerates cold but no real frost. Ipomoea nil 'Scarlett O'Hara' shrugs off cold nights but a real, sustained freeze will kill it.

Concretely, for ipomoea nil 'scarlett o'hara' as it gets too cold:

Down to roughly about 1 to 5 °C it copes, especially if dry and sheltered.
A sustained hard frost collapses the top growth; whether it returns depends on whether the roots, crown or tubers froze.
Wet cold is far more lethal than dry cold for this plant — soggy, frozen soil is the usual killer.

Can ipomoea nil 'scarlett o'hara' go outside or overwinter — and where?

It can live outside year-round only in the mildest, most sheltered part of USDA 2-11 (frost-tender warm-season annual) or a frost-free UK microclimate.
In colder zones, grow it in a pot you can move under cover, or lift its tubers/roots and store them frost-free over winter.
A south-facing wall, free-draining soil and a dry winter position can push it a full zone hardier than the books suggest.

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 ipomoea nil 'scarlett o'hara' can be outside. US growers can check USDA zones; UK growers should use the RHS hardiness ratings, which match the H2 figure above.

Frost protection for borderline ipomoea nil 'scarlett o'hara'

Ipomoea nil 'Scarlett O'Hara' is right on a hardiness edge in many gardens, so if you are pushing it, these measures buy it the margin it needs:

Mulch the crown or root zone deeply with bark, straw or leaf-mould before the first hard frost.
Move container plants against a warm wall or into an unheated but frost-free porch or greenhouse.
Fleece the top growth on the coldest nights, and keep it on the dry side — dry roots survive cold far better than wet ones.
Lift dahlia-type tubers or tender crowns after the first light frost blackens the foliage and store them somewhere cool but frost-free.

Ipomoea nil 'Scarlett O'Hara' hardiness — frequently asked questions

Is ipomoea nil 'scarlett o'hara' cold hardy?

Ipomoea nil 'Scarlett O'Hara' is half-hardy (RHS H2). It survives a mild winter outdoors in a sheltered spot, but a hard frost kills it — so in colder zones it is lifted, potted, or grown as a tender plant. Borderline outdoors. In its mild end of USDA 2-11 (frost-tender warm-season annual) (and sheltered UK gardens) ipomoea nil 'scarlett o'hara' can stay out; in colder areas it must be lifted, brought in, or treated as a frost-tender plant.

What is the minimum temperature ipomoea nil 'scarlett o'hara' can survive?

Minimum survivable temperature is roughly about 1 to 5 °C — tolerates cold but no real frost. Ipomoea nil 'Scarlett O'Hara' shrugs off cold nights but a real, sustained freeze will kill it.

What hardiness zone is ipomoea nil 'scarlett o'hara'?

Ipomoea nil 'Scarlett O'Hara' is rated USDA 2-11 (frost-tender warm-season annual) and RHS H2 — Tender — survives a frost-free greenhouse or a very mild, sheltered spot.

Can ipomoea nil 'scarlett o'hara' survive winter outside?

It can live outside year-round only in the mildest, most sheltered part of USDA 2-11 (frost-tender warm-season annual) or a frost-free UK microclimate. In colder zones, grow it in a pot you can move under cover, or lift its tubers/roots and store them frost-free over winter. A south-facing wall, free-draining soil and a dry winter position can push it a full zone hardier than the books suggest.

How do I protect ipomoea nil 'scarlett o'hara' from frost?

Mulch the crown or root zone deeply with bark, straw or leaf-mould before the first hard frost. Move container plants against a warm wall or into an unheated but frost-free porch or greenhouse. Fleece the top growth on the coldest nights, and keep it on the dry side — dry roots survive cold far better than wet ones. Lift dahlia-type tubers or tender crowns after the first light frost blackens the foliage and store them somewhere cool but frost-free.