Iris Iris hybrids
Just about everyone has grown iris at some time. But if you’ve noticed yours aren’t blooming like they used to, it may be time to divide — every three to five years is a good rule of thumb. You can move your iris any time if necessary, but dividing them in mid- to late summer is best. It gives the rhizomes enough time to establish a good root system before winter.
Start by trimming the foliage back to 10 to 12 in. to make plants easier to handle. Use a garden fork to lift the clump out of the ground. Then break or cut off the new growth, which is usually along the outside, from the center of the clump, and discard the old rhizomes. Replant the divisions right at the soil’s surface so they don’t rot.
TYPE Perennial SIZE 8 to 49 in. tall and 18 in. wide BLOOM Almost every color in spring LIGHT Full sun SOIL Well-drained PESTS Occasional iris borer HARDINESS Cold: USDA zones 4 to 9; Heat: AHS zones 9 to 1