Understand that one major genus of calla lily exists, called Zantedeschia. Under that genus category, 28 known species of calla lily exist. All are suitable for growing in submerged conditions, although you must exercise care to avoid waterlogging the upper portion of the plants. The choice of species is dependent upon budget, availability and color preference.
Plant calla lilies in submersible pots with ample drainage holes located along the bottom of each pot, an important element in planting calla lilies in water gardens and ponds; the continual supply of water will flow through the root system and thus keep the plant optimally moist. Plant calla lilies in a nutrient-rich, densely packed soil that will stand up to underwater submersion.
Choose the Zantedeschia hybrida variety of a calla lily for submerged areas where moderate amounts of drainage are available. Choose this version of calla lily when you want to grow nontraditional calla lily colors such as red, orange or pink blooms. This hybrida variety prefers moist soil, even though it is not suitable for areas where the plant will remain completely submerged in water. Instead, it is best suited for water gardens and ponds with a high shelf so the plant touches the top layer of water and is provided continual water but not completely submerged.
Zantedeschia aethiopica, a calla lily derived from rhizomes, is notable because of the large white flowers the plant produces. Hailing from South Africa, this kind of calla lily is tolerant of heat and wet weather conditions. Submerge this type of calla lily in ponds and water gardens by placing the plant either on a bottom, middle or top shelf layer. Adding a layer of rocks or pebbles to the bottom of the pot assists in keeping the pot completely submerged.