Cold hardiness & minimum temperature

Is Blue Morning Glory (Ipomoea indica)cold hardy? Hardiness zone & min temp

Also called Ocean Blue Morning Glory, Blue Dawn Flower, Koali Awa.

More about blue morning glory

About Blue Morning Glory

Ipomoea indica · also called Ocean Blue Morning Glory, Blue Dawn Flower · tropical

Ipomoea indica is a fast-growing, twining tropical vine producing abundant vivid blue-to-purple funnel-shaped flowers that open in the morning. It thrives in full sun with warm temperatures and is widely naturalised in frost-free regions. All parts are toxic — seeds contain ergine alkaloids and foliage is harmful to pets.

Cold limit: USDA 9-11 · RHS H1c (15-30°C)

Watch for — Invasive growth: Can become invasive in frost-free regions; cut back hard after flowering and remove self-seeded plants promptly.

What blue morning glory's hardiness rating actually means

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

Concretely, for blue morning glory 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 blue morning glory 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 blue morning glory can be outside. US growers can check USDA zones; UK growers should use the RHS hardiness ratings, which match the H1c figure above.

Blue Morning Glory hardiness — frequently asked questions

Is blue morning glory cold hardy?

Blue Morning Glory 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. Blue Morning Glory can only live outside year-round in genuinely frost-free climates (roughly USDA 9-11); everywhere else it is a houseplant that summers out at most.

What is the minimum temperature blue morning glory can survive?

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

What hardiness zone is blue morning glory?

Blue Morning Glory is rated USDA 9-11 and RHS H1c — Warm-temperate — can summer outdoors but must come in well before the first frost.

Can blue morning glory 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 blue morning glory 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.