Garden Guides advises gardeners to fertilize a reblooming iris with a 6-10-10 mixture, after the first bloom. Prune the iris between blooms, cutting the stalks all the way to the base. Do not remove the leaves. Divide the iris every three to four years.Continue Reading
Reblooming irises prefer locations with full sun and well-drained, slightly acidic soil. They are hardy in U.S. Department of Agriculture zones 3 through 10, with more northern climates experiencing a reduction in bloom repetition. While most irises bloom once, reblooming irises bloom 2 to 4 times after their initial bloom in the spring. Many bloom into the fall.
North Carolina State University explains that the large majority of reblooming irises are bearded irises. Bearded irises grow from 8 inches to 4 feet tall. They have 3 upright petals and 3 hanging petals. A fuzzy line called a beard runs down the middle of the flower. Underground stems called rhizomes store food for the plant. Offsets develop from the original rhizome.
If planted in too much shade, an iris often fails to bloom. Using too much fertilizer or planting the rhizome too deep can also cause this problem. Bacterial soft rot can affect the rhizomes if they are left standing in water too long. Iris borers sometimes attack the plant, leaving small notches. This can require the use of a registered insecticide in the spring as new growth occurs.Learn more about Outdoor Plants & Flowers