Calla lilies grow from horizontal root stems called rhizomes. A once-thriving, blooming calla lily bed, can stop flowering the next year. This is most likely because the rhizomes have self-multiplied and are overcrowded. Too many bulbs are vying for the same nutrients and water, a very unfavourable situation for the rhizomes. Fortunately, you can easily divide calla lilies and give the extras to friends or family or you can start a new calla lily bed.
Cut back the calla lily foliage to the ground after flowering when the leaves turn yellow, a sign it's dying back for the winter.
Lift calla lily rhizomes from the soil. Use a pitch fork and keep in mind that the rhizomes are only planted a couple inches beneath the soil.
Dry them if the rhizomes are tender in your climate and you are storing them for the winter. Dry them for several days in a shady area before dividing.
Brush off the dirt and you'll see all the different rhizomes that have grown over the years.
Divide the rhizomes with a utility or another sharp knife. Each section should have a minimum of one bud or eye. Replant or store as soon as possible.