With several hundred species and cultivars, irises vary greatly in color, shape and size. Some serve as short ground covers, while others are up to 4 feet tall. Some irises are rebloomers, meaning they can bloom a second time in the summer or fall after the initial spring blooming cycle. It's possible to keep your irises blooming year to year and to have rebloomers bloom a second time with a little care.
Fertilize irises in the spring when new growth emerges. Sprinkle a low-nitrogen fertilizer, such as 5-10-10, or bone meal around the plants, but don’t let it touch the rhizomes. It’s better to use less than the recommended amount than more. For reblooming irises, fertilize again a month after the initial blooms appear to help them bloom again.
Clip off spent iris blooms and the stalks if you are growing reblooming irises. This will help keep them blooming. For irises that are not rebloomers, clip off the spent blooms to help the irises bloom the following year.
Divide overcrowded iris beds every three to five years in the late summer or early fall. If your irises have fewer blooms than previous years, they may be overcrowded. Dig up the rhizomes and separate them, then replant them 12 to 24 inches apart.
Remove weeds and grasses from the iris bed so there is less competition for water and nutrients from the soil. Water established irises during extremely hot weather when rainfall is limited.
Things You Will Need
- Hand clippers