Zantedeschia comes in two broad types: Arum lilies and Calla lilies. Arum lilies are hardy down to around -10 degrees celsius, meaning that they’ll survive most UK winters, while Calla lilies are frost tender and often require winter protection. Zandeschia aethiopica is an Arum lily, so relatively frost hardy, although it’s best to give it a deep winter mulch to be on the safe side if you live in a frost-prone area.
Like other members of the Araceae family, these lilies absolutely love a poorly-drained soil. If your garden soil is well-drained, decrease drainage by lining your planting spot with plastic and punching a few holes in the bottom.