Cold hardiness & minimum temperature

Is Euphorbia tirucalli 'Firesticks' (Euphorbia tirucalli 'Firesticks')cold hardy? Hardiness zone & min temp

Also called firesticks, red pencil tree, sticks on fire.

More about euphorbia tirucalli 'firesticks'

About Euphorbia tirucalli 'Firesticks'

Euphorbia tirucalli 'Firesticks' · also called firesticks, red pencil tree · houseplant

Euphorbia tirucalli 'Firesticks' is a near-leafless succulent of slender pencil-thick stems that flush coral, orange and red in bright light and cool weather, greening up in shade. It thrives on neglect in fast-draining soil and full sun, but its caustic milky sap is hazardous, so handle it with care.

Cold limit: USDA 10-11 (indoor in most US and UK homes) · RHS H1c (18-27C)

Watch for — Loss of red colour: Stems fade to green in insufficient light or warm, even temperatures. Restore brighter, cooler, sunnier conditions to bring back the firesticks colouring.

What euphorbia tirucalli 'firesticks''s hardiness rating actually means

Euphorbia tirucalli 'Firesticks' 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 10-11 (indoor in most US and UK 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 5 °C (and never frost). Euphorbia tirucalli 'Firesticks' has no frost tolerance at all — it is an indoor plant in any climate with a real winter.

Concretely, for euphorbia tirucalli 'firesticks' 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 euphorbia tirucalli 'firesticks' 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 euphorbia tirucalli 'firesticks' can be outside. US growers can check USDA zones; UK growers should use the RHS hardiness ratings, which match the H1c figure above.

Euphorbia tirucalli 'Firesticks' hardiness — frequently asked questions

Is euphorbia tirucalli 'firesticks' cold hardy?

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

What is the minimum temperature euphorbia tirucalli 'firesticks' can survive?

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

What hardiness zone is euphorbia tirucalli 'firesticks'?

Euphorbia tirucalli 'Firesticks' is rated USDA 10-11 (indoor in most US and UK homes) and RHS H1c — Warm-temperate — can summer outdoors but must come in well before the first frost.

Can euphorbia tirucalli 'firesticks' 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 euphorbia tirucalli 'firesticks' 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.