Cold hardiness & minimum temperature

Is African Milk Tree (Euphorbia trigona)cold hardy? Hardiness zone & min temp

Also called African milk tree, African milk bush, Cathedral cactus, Candelabra cactus, Friendship cactus, Good luck cactus.

More about african milk tree

About African Milk Tree

Euphorbia trigona · also called African milk tree, African milk bush · houseplant

The African milk tree (Euphorbia trigona) is an upright, candelabra-shaped succulent grown as an easy-care houseplant. Give it bright light, a gritty cactus mix and infrequent watering once the soil dries. It is not pet-safe: its milky latex sap irritates skin, eyes and the gut, so keep it away from pets and children.

Cold limit: USDA 9a-11b (grown as a houseplant or summer container plant in cooler zones) (18-29 C (avoid below ~7 C))

What african milk tree's hardiness rating actually means

African Milk Tree 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 9a-11b (grown as a houseplant or summer container plant 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 10 °C (sustained cold below this is damaging). African Milk Tree has no frost tolerance at all — it is an indoor plant in any climate with a real winter.

Concretely, for african milk tree 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 african milk tree 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 african milk tree can be outside. US growers can check USDA zones; UK growers should use the RHS hardiness ratings, which match the H1b figure above.

African Milk Tree hardiness — frequently asked questions

Is african milk tree cold hardy?

African Milk Tree 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. African Milk Tree can only live outside year-round in genuinely frost-free climates (roughly USDA 9a-11b (grown as a houseplant or summer container plant in cooler zones)); everywhere else it is a houseplant that summers out at most.

What is the minimum temperature african milk tree can survive?

What hardiness zone is african milk tree?

African Milk Tree is rated USDA 9a-11b (grown as a houseplant or summer container plant in cooler zones) and RHS H1b — Sub-tropical — a normal warm home is fine, but it cannot go outside in a cool season.

Can african milk tree 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 african milk tree 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.