Cold hardiness & minimum temperature

Is Zantedeschia 'Hot Chocolate' (Zantedeschia 'Hot Chocolate')cold hardy? Hardiness zone & min temp

Also called Hot Chocolate calla lily, chocolate-maroon calla.

More about zantedeschia 'hot chocolate'

About Zantedeschia 'Hot Chocolate'

Zantedeschia 'Hot Chocolate' · also called Hot Chocolate calla lily, chocolate-maroon calla · flowering

Zantedeschia 'Hot Chocolate' is a hybrid calla lily with rich brown to maroon spathes flushed ruby, set against dark green foliage. This tender tuberous perennial wants warmth, bright light and fertile, moist, free-draining soil. Lift and store the rhizome dry in frost-prone areas. A bold container and border plant reaching roughly 50-75 cm.

Cold limit: USDA 8-10 (lift and store below zone 8) · RHS H3 (15-24°C)

Watch for — Rhizome rot: Overwatering and cold, wet soil cause soft rot. Use a free-draining mix, water moderately, and keep dormant rhizomes dry and frost-free.

What zantedeschia 'hot chocolate''s hardiness rating actually means

Zantedeschia 'Hot Chocolate' 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 (lift and store below zone 8) — 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. Zantedeschia 'Hot Chocolate' shrugs off cold nights but a real, sustained freeze will kill it.

Concretely, for zantedeschia 'hot chocolate' 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 zantedeschia 'hot chocolate' go outside or overwinter — and where?

It can live outside year-round only in the mildest, most sheltered part of USDA 8-10 (lift and store below zone 8) 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 zantedeschia 'hot chocolate' 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 zantedeschia 'hot chocolate'

Zantedeschia 'Hot Chocolate' 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.

Zantedeschia 'Hot Chocolate' hardiness — frequently asked questions

Is zantedeschia 'hot chocolate' cold hardy?

Zantedeschia 'Hot Chocolate' 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 (lift and store below zone 8) (and sheltered UK gardens) zantedeschia 'hot chocolate' can stay out; in colder areas it must be lifted, brought in, or treated as a frost-tender plant.

What is the minimum temperature zantedeschia 'hot chocolate' can survive?

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

What hardiness zone is zantedeschia 'hot chocolate'?

Zantedeschia 'Hot Chocolate' is rated USDA 8-10 (lift and store below zone 8) and RHS H3 — Half-hardy — comes through mild UK winters outside but is killed by a hard freeze.

Can zantedeschia 'hot chocolate' survive winter outside?

It can live outside year-round only in the mildest, most sheltered part of USDA 8-10 (lift and store below zone 8) 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 zantedeschia 'hot chocolate' 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.