Calla lilies are not "true" lilies, and grow long, tube-shaped flowers rather than star-shaped blooms. Callas grow in all shades but blue, and rebloom year after year from perennial bulbs. Like all flowers, calla lilies produce seeds when pollinated, and can go to seed to propagate new plants. If you grow calla lilies and feel up to the challenge, look for seed pods in your mature calla lily blooms, remove the pods and replant them to germinate your own callas.
Look for seed pods at the centre of mature calla lily blooms. The pods resemble small bulbs, and should be light green. Pull these pods out of the blooms when the flowers droop to the side, as they'll soften and rot if you leave them until the bloom fades completely. Use a set of tweezers to pull the pods out without ruining the blooms.
Dampen a paper towel and lay it on a plate, in a safe spot. Spread your calla lily pods on the paper towel, and make sure that none are touching. Cover the pods with another damp paper towel and leave them. Maintain moisture in the paper towels and expect germination in three to five days. Throw out pods that don't sprout.
Prepare one starter pot per calla lily pod. Fill the pots three-quarters full with starter potting soil and plant the pods just under the soil's surface. Set each pot in a dish of water, so the water wicks up into the soil. Direct watering will cause the pods to rot in the soil. Spray the surface of each pot with two to three bursts from a squirt bottle to maintain surface moisture without overwatering the pods. Expect growth in one to two weeks.