Zantedeschia aethiopica (probably Green Goddess) below was on an outside exhibit at Chelsea 2012.
Zantedeschia plant (such as Zantedeschia Natural Bouquet, above) likes to be watered and fed regularly, but is reasonably hardy and can survive periods of both drought and minor frosts (some varieties can survive very cold conditions and others don’t like any cold).
Burncoose Nurseries stand at Chelsea 2012 in the photo above, it is a good choice for growing beside streams or ponds.
If it is planted in a drier area it is better grown in partial shade. It won’t flower well in deeper shade.