Cold hardiness & minimum temperature

Is Forked Aichryson (Aichryson dichotomum)cold hardy? Hardiness zone & min temp

Also called Forked Aichryson, Tree of Love.

More about forked aichryson

About Forked Aichryson

Aichryson dichotomum · also called Forked Aichryson, Tree of Love · houseplant

A biennial or short-lived perennial succulent endemic to the Canary Islands (Tenerife, Gran Canaria, La Palma, Hierro, Gomera), growing 20–40 cm tall with dichotomously branching stems covered in soft hairs. Bright yellow star flowers appear in spring and summer. Grows in laurel-forest shade; prefers cool, bright conditions indoors with a distinct winter rest.

Cold limit: USDA 9b-11 · RHS H3 (2–28°C)

Watch for — Etiolation in low light: Stems stretch dramatically and weaken in insufficient light, especially in winter. Supplement with a grow light or move to the brightest available position. Biennial plants naturally die after flowering and should be replaced with cuttings.

What forked aichryson's hardiness rating actually means

Forked Aichryson is half-hardy (RHS H3). It survives a mild winter outdoors in a sheltered spot, but a hard frost kills it — so in colder zones it is lifted, potted, or grown as a tender plant. Its RHS rating of H3 means: Half-hardy — comes through mild UK winters outside but is killed by a hard freeze. On the US scale that maps to USDA 9b-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 to 1 °C — a light, short frost only. Forked Aichryson shrugs off cold nights but a real, sustained freeze will kill it.

Concretely, for forked aichryson as it gets too cold:

Down to roughly about −5 to 1 °C it copes, especially if dry and sheltered.
A sustained hard frost collapses the top growth; whether it returns depends on whether the roots, crown or tubers froze.
Wet cold is far more lethal than dry cold for this plant — soggy, frozen soil is the usual killer.

Can forked aichryson go outside or overwinter — and where?

It can live outside year-round only in the mildest, most sheltered part of USDA 9b-11 or a frost-free UK microclimate.
In colder zones, grow it in a pot you can move under cover, or lift its tubers/roots and store them frost-free over winter.
A south-facing wall, free-draining soil and a dry winter position can push it a full zone hardier than the books suggest.

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 forked aichryson can be outside. US growers can check USDA zones; UK growers should use the RHS hardiness ratings, which match the H3 figure above.

Frost protection for borderline forked aichryson

Forked Aichryson is right on a hardiness edge in many gardens, so if you are pushing it, these measures buy it the margin it needs:

Mulch the crown or root zone deeply with bark, straw or leaf-mould before the first hard frost.
Move container plants against a warm wall or into an unheated but frost-free porch or greenhouse.
Fleece the top growth on the coldest nights, and keep it on the dry side — dry roots survive cold far better than wet ones.
Lift dahlia-type tubers or tender crowns after the first light frost blackens the foliage and store them somewhere cool but frost-free.

Forked Aichryson hardiness — frequently asked questions

Is forked aichryson cold hardy?

Forked Aichryson is half-hardy (RHS H3). It survives a mild winter outdoors in a sheltered spot, but a hard frost kills it — so in colder zones it is lifted, potted, or grown as a tender plant. Borderline outdoors. In its mild end of USDA 9b-11 (and sheltered UK gardens) forked aichryson can stay out; in colder areas it must be lifted, brought in, or treated as a frost-tender plant.

What is the minimum temperature forked aichryson can survive?

Minimum survivable temperature is roughly about −5 to 1 °C — a light, short frost only. Forked Aichryson shrugs off cold nights but a real, sustained freeze will kill it.

What hardiness zone is forked aichryson?

Forked Aichryson is rated USDA 9b-11 and RHS H3 — Half-hardy — comes through mild UK winters outside but is killed by a hard freeze.

Can forked aichryson survive winter outside?

It can live outside year-round only in the mildest, most sheltered part of USDA 9b-11 or a frost-free UK microclimate. In colder zones, grow it in a pot you can move under cover, or lift its tubers/roots and store them frost-free over winter. A south-facing wall, free-draining soil and a dry winter position can push it a full zone hardier than the books suggest.

How do I protect forked aichryson from frost?

Mulch the crown or root zone deeply with bark, straw or leaf-mould before the first hard frost. Move container plants against a warm wall or into an unheated but frost-free porch or greenhouse. Fleece the top growth on the coldest nights, and keep it on the dry side — dry roots survive cold far better than wet ones. Lift dahlia-type tubers or tender crowns after the first light frost blackens the foliage and store them somewhere cool but frost-free.