Bearded irises (Iris germanica) are popular perennials in this area, grown for their stunning flowers. So named because of their fuzzy “beards” in the three downward falling petals, bearded irises bloom from spring through summer and make excellent cut flowers.
These plants are grown from rhizomes, which are underground stems. The rhizomes multiply each year and can be divided easily. In fact, they should be lifted and divided about every 5 years. June and July are the best times to divide.
To divide, cut the foliage back to about 6 inches. Dig around the perimeter of the planting to loosen the rhizomes with a gardener’s fork. Using your hands, lift the plantings. Brush off the soil, and remove and trash any diseased, rotten, or old woody parts of the rhizomes. Look for the iris borers and if you see them or damage caused by them, remove and trash. Separate the rhizomes so that each one has a fan of leaves. Save only healthy rhizomes with foliage attached.
Spread out and bury the roots and bury the rhizomes deep enough for them to remain stable but shallow enough so their top sides are exposed. Do not mulch. Plant about 12 to 24 inches apart, depending on the plant’s mature size. Water thoroughly and water until established.
Bearded irises should be planted in well-drained soil, in full sun, and with good air circulation. Soil with too much clay should be amended with organic matter or compost to improve the drainage. When they are established, they are drought tolerant. Deer are not interested in bearded irises.
These irises benefit from deadheading and a shot of fertilize in the summer. To minimize pests, the foliage is trimmed to about 6 inches in the fall. Throw away the foliage, do not put in the compost pile.
The American Iris Society (AIS) has a local region, Region IV, for Virginia, Maryland, and DC. If you are interested in joining or learning of iris shows and sales, visit the Region IV website. AIS has divided the bearded iris into six groups, listed below in order of earliest to latest bloom time and shortest to tallest sizes.
- Miniature Dwarf Bearded (MDB): These are 4 to 8 inches tall, earliest to bloom, and used in rock gardens or planted in drifts. The flowers are small, one to 2 inches across. They can bloom as early as March, depending on the zone.
- Standard Dwarf Bearded (SDB): These are 8 to 16 inches tall, the flowers are larger, and tend to bloom early in spring (April). They are best grown in clumps.
- Intermediate Bearded (IB): These are 16 to 27 ½ inches tall and bloom in April and May and can be grown in clumps or along a garden border.
- Border Bearded (BB): These are 16 to 27 ½ inches tall and bloom in early summer, same time as Tall Bearded but with a shorter height.
- Miniature Tall Bearded (MTB): These are 16 to 27 ½ inches tall. The stems are thinner, and the flower sizes are smaller than Border Bearded and Tall Bearded but bloom at the same time. Often called table irises because they are good for cut arrangements.
- Tall Bearded (TB): These are 27 ½ inches tall and taller and may need staking. They have a lot of branching and many buds. Typically, these are summer bloomers but the timing of the bloom varies with the cultivar so they can bloom from late spring to early summer.
Because there are thousands of cultivars, it may be best to choose from award-winning irises listed on the AIS or Region IV websites. Each year, the AIS gives awards to the different classification of irises, including the six types of bearded irises. In addition, the AIS sponsors the tall bearded iris symposium, which is an annual popularity poll of tall bearded irises. AIS members and nonmembers may vote. The top irises are ranked, and the results are published on the website. The list provides the plant’s rank in the current year and previous year, cultivar name, votes received, hybridizer’s name, introduction year, bloom season, height, and a brief description of the flower color.
Bearded irises are available at local garden centers. For a wider variety, check out these bulb companies. Try growing these in your garden this year!