Zantedeschia aethiopica ‘White Giant’ by far the largest Calla lily I have seen. Mature well grown plants can reach 7 feet tall. Expect this in subtropical areas, here in the north you can expect between 3 to 5 feet depending on feeding and maturity. Plants have large hastate leaves 1 to 2 feet long and around 8 to 12 inches wide on mature plants. Each leaf is dark green with white spots. As the plant matures flowers will emerge and grow above the foliage. These beautiful flowers are white and large mature plants can produce flowers over 1 foot tall and wide. These massive flowers are held high on large petioles that reach up to 6 feet. Hardy to zone 7 can survive in zone 6 if well mulched in winter.