Cold hardiness & minimum temperature

Is Pink Calla Lily (Zantedeschia rehmannii)cold hardy? Hardiness zone & min temp

Also called Pink Calla Lily, Pink Arum, Rehmann's Calla.

More about pink calla lily

About Pink Calla Lily

Zantedeschia rehmannii · also called Pink Calla Lily, Pink Arum · flowering

Zantedeschia rehmannii is the original pink calla lily native to eastern South Africa, producing slender, lance-shaped leaves and elegant funnel-shaped spathes in shades of soft pink to deep rose. It grows from rhizomes, thrives in moist to wet conditions, and suits containers, borders, and cutting gardens. Toxic to pets due to calcium oxalate; dies back to rhizome in winter.

Cold limit: USDA 8–10 · RHS H3 (10–25°C)

Watch for — Rhizome rot: Overwatering during or especially after the growing season causes rhizome rot. Ensure excellent drainage in containers and allow the rhizome to dry off completely during winter dormancy. In cold, wet climates, lift and store rhizomes frost-free.

What pink calla lily's hardiness rating actually means

Pink Calla Lily 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 8–10 — 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. Pink Calla Lily shrugs off cold nights but a real, sustained freeze will kill it.

Concretely, for pink calla lily 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 pink calla lily go outside or overwinter — and where?

It can live outside year-round only in the mildest, most sheltered part of USDA 8–10 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 pink calla lily 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 pink calla lily

Pink Calla Lily 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.

Pink Calla Lily hardiness — frequently asked questions

Is pink calla lily cold hardy?

Pink Calla Lily 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 8–10 (and sheltered UK gardens) pink calla lily can stay out; in colder areas it must be lifted, brought in, or treated as a frost-tender plant.

What is the minimum temperature pink calla lily can survive?

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

What hardiness zone is pink calla lily?

Pink Calla Lily is rated USDA 8–10 and RHS H3 — Half-hardy — comes through mild UK winters outside but is killed by a hard freeze.

Can pink calla lily survive winter outside?

It can live outside year-round only in the mildest, most sheltered part of USDA 8–10 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 pink calla lily 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.