Culture
Grow in average, medium moisture, well-drained soils in full sun. Tolerates some part afternoon shade, particularly in hot summer climates. Best with consistent moisture from spring to 6 weeks after flowering ends. Some drought tolerance once established. Best performance occurs in light sandy soils with excellent drainage. With clay soils or in areas of high rainfall, plant rhizomes on slopes (growing end uphill) or in raised beds to promote good drainage and discourage the onset of rhizome rot. Plant rhizomes, depending on location, from late July through October (late July–early September in areas with cold winters or September-October in areas with mild winters). Plant rhizomes 12-20” apart. Plant each rhizome shallowly over a baseball-sized mound of soil with 1/3 of the rhizome above the soil and with the roots horizontally spread to support the plant. Growth comes from the leafy end of the rhizome. If overcrowding occurs over time, lift the clump in late summer (August) with a garden fork, divide and replant. Keep the iris bed free of weeds.
Noteworthy Characteristics
Tall Bearded Iris is a rhizomatous iris class whose numerous hybrid cultivars grow to heights above 27.5” tall featuring two or more branches and 7 or more blossoms per stem with flowers spreading to more than 5” wide. Each flower has upright standards and pendant falls. Flowers bloom in June (St. Louis). Most cultivars produce plants significantly taller than 27.5”, with many rising to 38-40” tall. Bearded name comes from the bushy beard which is easily visible in the middle of each fall. Plants typically form clumps in the garden over time. Flowers bloom in an almost unlimited variety of different colors and color combinations. Narrow, linear green leaves are substantially erect.
Genus named for the Greek goddess of the rainbow.
'Midnight Fragrance' is a tall bearded iris which typically grows to 36" tall and slowly spreads by rhizomes. As the cultivar name suggests, blooms are sweetly fragrant. Standards and falls are dark violet black and ruffled. Blooms in spring. Sword-shaped, linear leaves. C. Hahn 1989.
Problems
Leaf spot, root rot, bacterial soft rot, crown rot and mosaic viruses may appear. Watch for slug, snails, whiteflies, aphids and thrips. Iris borers can cause significant problems in areas where they are found.
The major insect pest of bearded iris is iris borer. Major disease problems are bacterial soft rot and fungal leaf spot. Good sanitation practices are the most important component of any disease/insect control program: promptly remove and destroy diseased foliage/rhizomes, promptly remove and destroy borer-infected foliage/rhizomes and perform an annual clean-up of all debris and foliage from beds in fall after frost. The most frequent causes of failure to flower or sparse flowering are (1) rhizomes are planted too deep, (2) plants are located in too much shade, (3) plants were given too much fertilizer or (4) plants have become overcrowded and need division.
Uses
Best grouped or massed in sunny areas of perennial beds, borders or foundations.