Cold hardiness & minimum temperature

Is Euphorbia cylindrifolia (Euphorbia cylindrifolia)cold hardy? Hardiness zone & min temp

Also called cylindrical-leaf euphorbia, Madagascar cylinder euphorbia.

More about euphorbia cylindrifolia

About Euphorbia cylindrifolia

Euphorbia cylindrifolia · also called cylindrical-leaf euphorbia, Madagascar cylinder euphorbia · houseplant

A dwarf Madagascan caudiciform succulent forming a knobbly underground tuber and a low mat of slender, branching grey-brown stems tipped with small, narrow, cylindrical greyish leaves. Slow and compact, it suits shallow bonsai-style pots and demands bright light, sharp drainage and a dry winter rest. A choice, miniature collector's plant.

Cold limit: USDA 10-11 (indoor in most US homes) · RHS H1b (15-29°C)

Watch for — Tuber and root rot: Overwatering or a too-dense mix rots the tuber. Use gritty, shallow planting, let the soil dry between waterings, and keep it dry in winter.

What euphorbia cylindrifolia's hardiness rating actually means

Euphorbia cylindrifolia 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 10-11 (indoor in most US homes) — 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). Euphorbia cylindrifolia has no frost tolerance at all — it is an indoor plant in any climate with a real winter.

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

Euphorbia cylindrifolia hardiness — frequently asked questions

Is euphorbia cylindrifolia cold hardy?

Euphorbia cylindrifolia 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. Euphorbia cylindrifolia can only live outside year-round in genuinely frost-free climates (roughly USDA 10-11 (indoor in most US homes)); everywhere else it is a houseplant that summers out at most.

What is the minimum temperature euphorbia cylindrifolia can survive?

What hardiness zone is euphorbia cylindrifolia?

Euphorbia cylindrifolia is rated USDA 10-11 (indoor in most US homes) and RHS H1b — Sub-tropical — a normal warm home is fine, but it cannot go outside in a cool season.

Can euphorbia cylindrifolia 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 euphorbia cylindrifolia 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.