Cold hardiness & minimum temperature

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

Also called Arum Lily, Calla Lily, White Calla, Pig Lily.

More about arum lily

About Arum Lily

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

Zantedeschia aethiopica is a robust, rhizomatous perennial native to stream banks, marshes, and moist meadows in southern Africa, producing large, pure-white spathe flowers surrounding a yellow spadix from late winter to early summer. It thrives in moist to wet, humus-rich soil in full sun to part shade and can be grown as a marginal aquatic with roots in shallow water. In the UK it is hardy enough to overwinter outdoors in most areas with mulch protection; in colder climates (USDA zones below 8) lift rhizomes and store frost-free. All parts are toxic to cats and dogs.

Cold limit: USDA 8-11 · RHS H4 (-5°C to 30°C)

Watch for — Rhizome Rot: Overwatering in cool or waterlogged conditions during winter dormancy causes fungal rot of the rhizome; allow soil to dry slightly between waterings from autumn onward and ensure good drainage outside the growing season.

What arum lily's hardiness rating actually means

Yes — arum lily is genuinely cold hardy. Rated RHS H4 and USDA 8-11, 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 8-11 — 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 −10 to −5 °C. Arum Lily is built for winter — once established it takes hard frost and snow in its stride.

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

Plant it out within USDA 8-11 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 arum lily can be outside. US growers can check USDA zones; UK growers should use the RHS hardiness ratings, which match the H4 figure above.

Arum Lily hardiness — frequently asked questions

Is arum lily cold hardy?

Yes — arum lily is genuinely cold hardy. Rated RHS H4 and USDA 8-11, it lives outdoors all year and needs winter cold rather than protection from it. An outdoor plant. Arum Lily is hardy across USDA 8-11; 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 arum lily can survive?

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

What hardiness zone is arum lily?

Arum Lily is rated USDA 8-11 and RHS H4 — Hardy in an average winter across much of the temperate world.

Can arum lily survive winter outside?

Plant it out within USDA 8-11 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 arum 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.