Do Bearded Irises Grow in Charleston, S.C.?

Cultivation

• Bearded irises grow from rhizomes that are similar in appearance to the ginger root you see at the market. Irises prefer alkaline, well-draining soil and a sunny location with dappled shade in the afternoon to keep the colors from fading. A soil test will help you determine what amendments are necessary. Work in a fertilizer high in potassium and phosphorus and low in nitrogen. Let the prepared bed lay fallow for a couple of weeks and then plant the rhizomes on the soil surface with a dusting of soil over them. Removing finished blooms and stalks encourages further growth and more flowers on the reblooming cultivars. Iris clumps are easily divided. In South Carolina, fall division is best done every few years.

Attributes

• Bearded iris is easily identified by the beard-like shape of its lower petals. Bloom sizes vary from cultivar to cultivar. They can be as small as 2 inches wide to massive 7-inch-wide flowers on strong stems, and there are numerous color choices. This group of irises bloom primarily in early summer. With bearded iris cultivars ranging in height from 2 inches tall to 5 feet, there are many possibilities on where to place them. The smallest cultivars bring brilliant color to the rock garden. They can be used to line a path or edge a rose garden. Consider placing them en masse around a bird bath or other garden ornament to highlight a classic Charleston side garden. Place taller varieties in the flower border with consideration to color balance and flow with other plants in the garden.

Bearded Iris Types

• Bearded irises fall into six sub-groups based on size. In general, the smaller cultivars are the first to bloom, so you could have a collection of irises all blooming at different times. Miniature dwarf bearded irises are the smallest, growing to 8 inches. A favorite miniature dwarf is "Bantam," which has dark reddish-purple flowers. Standard dwarf bearded irises grow to 15 inches. Consider the apricot-colored "Software" with pink edges. Intermediate bearded irises grow to 16 inches in height. Add some drama with "Red Zinger." Border bearded irises also grow to 16 inches, but bloom a little later than the intermediate irises. "New Wave" is pure white. Miniature tall bearded irises have small blooms, but tall bearded irises are the queens and there are thousands of cultivars in this sub-group. In USDA zones 8a to 9a, some will rebloom in late summer or fall.

Other Considerations

• Bacterial soft rot and iris borer are two potential issues to watch for. If the rhizome is damaged and sits in poorly drained soil, the iris borer enters through the damaged portion of the rhizome and devours it from the inside out. It's important to keep the area around the plants free of leaf debris. When you divide iris clumps in fall, destroy any rhizomes that appear weak or infested. Avoid using manure as it promotes soft rot. Avoid planting in full shade, overusing fertilizer, overcrowding and planting the rhizomes too deep. The result will be poor growing habits and lanky stems.