Irises are grown from both seed and root separation. The roots, or Rhizomes, are easily separated and replanted. The Rhizome looks like a long, thin potato with roots underneath. When transplanting, separate the Rhizome. Make sure to have some root and a leaf or two in each section. Plant the Rhizomes near the surface with the roots below. Space them a foot or so apart . They will fill in the spaces quickly.