Cold hardiness & minimum temperature

Is Colocasia 'Illustris' (Imperial Taro) (Colocasia esculenta 'Illustris')cold hardy? Hardiness zone & min temp

Also called Imperial Taro, Imperial Elephant Ear, Black Elephant Ear, Illustris Elephant Ear.

More about colocasia 'illustris' (imperial taro)

About Colocasia 'Illustris' (Imperial Taro)

Colocasia esculenta 'Illustris' · also called Imperial Taro, Imperial Elephant Ear · tropical

Colocasia 'Illustris' is a tuberous tropical grown for huge heart-shaped, blackish-purple leaves veined in bright green. It wants warmth, bright light and constantly moist, rich soil, plus regular feeding. It is toxic: the ASPCA lists Colocasia esculenta as poisonous to cats, dogs and horses, so keep it well away from pets.

Cold limit: USDA USDA 7b-11 (corms hardy to about zone 7b with heavy mulch; grown as a tender perennial, lifted tuber or houseplant in colder zones) (18-29C)

Watch for — Yellowing leaves and mushy stems: Usually overwatering or cold, especially when the plant is slowing for dormancy. Cut back on water in autumn/winter and check the corm and roots for rot.

What colocasia 'illustris' (imperial taro)'s hardiness rating actually means

Colocasia 'Illustris' (Imperial Taro) 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 H1b means: Sub-tropical — a normal warm home is fine, but it cannot go outside in a cool season. On the US scale that maps to USDA USDA 7b-11 (corms hardy to about zone 7b with heavy mulch; grown as a tender perennial, lifted tuber or houseplant in colder 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 10 °C (sustained cold below this is damaging). Colocasia 'Illustris' (Imperial Taro) has no frost tolerance at all — it is an indoor plant in any climate with a real winter.

Concretely, for colocasia 'illustris' (imperial taro) as it gets too cold:

Below about about 10 °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 colocasia 'illustris' (imperial taro) go outside or overwinter — and where?

It can holiday outdoors in summer once nights are reliably above 10 °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 colocasia 'illustris' (imperial taro) can be outside. US growers can check USDA zones; UK growers should use the RHS hardiness ratings, which match the H1b figure above.

Colocasia 'Illustris' (Imperial Taro) hardiness — frequently asked questions

Is colocasia 'illustris' (imperial taro) cold hardy?

Colocasia 'Illustris' (Imperial Taro) 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. Colocasia 'Illustris' (Imperial Taro) can only live outside year-round in genuinely frost-free climates (roughly USDA USDA 7b-11 (corms hardy to about zone 7b with heavy mulch; grown as a tender perennial, lifted tuber or houseplant in colder zones)); everywhere else it is a houseplant that summers out at most.

What is the minimum temperature colocasia 'illustris' (imperial taro) can survive?

What hardiness zone is colocasia 'illustris' (imperial taro)?

Colocasia 'Illustris' (Imperial Taro) is rated USDA USDA 7b-11 (corms hardy to about zone 7b with heavy mulch; grown as a tender perennial, lifted tuber or houseplant in colder zones) and RHS H1b — Sub-tropical — a normal warm home is fine, but it cannot go outside in a cool season.

Can colocasia 'illustris' (imperial taro) survive winter outside?

It can holiday outdoors in summer once nights are reliably above 10 °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 colocasia 'illustris' (imperial taro) below its minimum temperature?

Below about about 10 °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.