Cold hardiness & minimum temperature

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

Also called Calla lily, Arum lily, White arum lily, Lily of the Nile, Pig lily, Florist's calla, Trumpet lily.

More about calla lily

About Calla Lily

Zantedeschia aethiopica · also called Calla lily, Arum lily · flowering

The calla lily is a moisture-loving, rhizomatous perennial prized for sculptural white spathes on tall stems. Give it bright indirect light or part shade, consistently damp rich soil, and warmth of 60-80F. Despite the name it is not a true lily but an aroid, and the ASPCA lists it as toxic to dogs and cats.

Cold limit: USDA USDA 8a-10b (can survive zone 7 with a thick winter mulch or by lifting and overwintering the rhizome indoors) (15-27C)

Watch for — Rhizome rot: The most common killer. Caused by waterlogged soil during dormancy or poor drainage in winter. Keep the rhizome cool and nearly dry while resting, and avoid leaving it in cold, sodden soil.

What calla lily's hardiness rating actually means

Yes — calla lily is genuinely cold hardy. Rated RHS H4 and USDA USDA 8a-10b (can survive zone 7 with a thick winter mulch or by lifting and overwintering the rhizome indoors), it lives outdoors all year and needs winter cold rather than protection from it. Its RHS rating of H4 means: Hardy in an average winter across much of the temperate world. On the US scale that maps to USDA USDA 8a-10b (can survive zone 7 with a thick winter mulch or by lifting and overwintering the rhizome indoors) — 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 to −5 °C. Calla Lily is built for winter — once established it takes hard frost and snow in its stride.

Concretely, for calla lily as it gets too cold:

It tolerates winter lows to about −10 to −5 °C once established.
Below its rated zone, the visible damage is browned or blackened top growth and, in the worst case, a killed crown or root.
First-year, newly planted, or container-grown specimens are noticeably less hardy than established garden plants — the roots are exposed.

Can calla lily go outside or overwinter — and where?

Plant it out within USDA USDA 8a-10b (can survive zone 7 with a thick winter mulch or by lifting and overwintering the rhizome indoors) and it overwinters with little or no help.
It does not want to come indoors — a warm winter room actually weakens a hardy plant by denying it dormancy.
The real risks in its range are waterlogging, wind-rock on young plants, and a late hard frost on new growth — not ordinary winter cold.

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 calla lily can be outside. US growers can check USDA zones; UK growers should use the RHS hardiness ratings, which match the H4 figure above.

Calla Lily hardiness — frequently asked questions

Is calla lily cold hardy?

Yes — calla lily is genuinely cold hardy. Rated RHS H4 and USDA USDA 8a-10b (can survive zone 7 with a thick winter mulch or by lifting and overwintering the rhizome indoors), it lives outdoors all year and needs winter cold rather than protection from it. An outdoor plant. Calla Lily is hardy across USDA USDA 8a-10b (can survive zone 7 with a thick winter mulch or by lifting and overwintering the rhizome indoors); it belongs in the ground or a frost-proof container, not on a windowsill, and many types actively need a cold winter to perform.

What is the minimum temperature calla lily can survive?

Minimum survivable temperature is roughly about −10 to −5 °C. Calla Lily is built for winter — once established it takes hard frost and snow in its stride.

What hardiness zone is calla lily?

Calla Lily is rated USDA USDA 8a-10b (can survive zone 7 with a thick winter mulch or by lifting and overwintering the rhizome indoors) and RHS H4 — Hardy in an average winter across much of the temperate world.

Can calla lily survive winter outside?

Plant it out within USDA USDA 8a-10b (can survive zone 7 with a thick winter mulch or by lifting and overwintering the rhizome indoors) and it overwinters with little or no help. It does not want to come indoors — a warm winter room actually weakens a hardy plant by denying it dormancy. The real risks in its range are waterlogging, wind-rock on young plants, and a late hard frost on new growth — not ordinary winter cold.

What happens to calla lily below its minimum temperature?

It tolerates winter lows to about −10 to −5 °C once established. Below its rated zone, the visible damage is browned or blackened top growth and, in the worst case, a killed crown or root. First-year, newly planted, or container-grown specimens are noticeably less hardy than established garden plants — the roots are exposed.