Lily of the Nile, or Agapanthus, includes six main species (two evergreens and four deciduous) and numerous additional hybrids, according to the Wisconsin Master Gardener Program. Agapanthus grows in clumps with long green grass-like or strappy leaves surrounding a two-to-three foot tall center stalk that hold clusters of showy blossoms in the summer. Native to southern Africa, lily of the Nile grows best in USDA hardiness zones 7 to 11. The plant grows from fleshy-type roots known as rhizomes that require splitting every four to six years in the beginning of the fall, once the blossoms fade.
Clear a planting site for the newly divided lily of the Nile that provides full sun and rich, moist soil. Mix in a three-inch layer of compost to a depth of six to 12 inches. Space the plants about eight inches away from other plants or objects.
Dig 12 inches out and down from the base of the plant with a shovel. Carefully lift up the clump of roots of the lily of the Nile.
Cut the root mass into pieces with a sharp knife and include some roots in each new division.
Plant the separated roots at the same depth or at least deep enough to bury the roots (rhizome).
Cover with dirt and then saturate with water to settle in place. Allow up to a year for the divided lily of the Nile plants to generate blooms.