Bearded irises are available in a rainbow of colors including whites, yellows, pinks, dark reds, oranges, purples and even black. Peak bloom time in the Lincoln area is in May, but the time to dig, divide and plant irises is in July and August, giving them 6-10 weeks before the first hard frost to become settled and develop new roots.
The rhizomes (tuber-like structures with roots coming off the bottom and a fan of leaves rising from one end) should be planted in well-drained soil, with the soil just covering the top of the rhizome by no more than half an inch.
Bearded irises need at least 6 hours of sunshine a day to bloom well. Once the planting site has been selected, work compost or aged manure into the soil. This is best incorporated in the soil at a depth that the feeder roots can grow down into it. Do not use fresh manure or poorly composted material, especially on top of the soil near the rhizomes, increasing chances for rot. Plant at least 18-24 inches from other perennials.
An easy way to plant is to make a small mound of soil within the planting hole, place the rhizome on top of the mound, and spread the roots down and out on either side of the mound. Fill soil around both sides of the mound and lightly over the top of the rhizome. Water well. If it does not rain, water again in 3-5 days and weekly after that if it remains dry. Once established, bearded irises are able to withstand long dry spells.
They need the most water during the spring growing season, when they require an inch of water per week, usually accomplished by normal rainfall. Do not mulch bearded irises during the growing season. Most mulches tend to keep the soil too wet, and also inhibit air movement around the rhizomes at the soil surface, resulting in rot. A covering of pine needles or other light airy material during the first winter is helpful in preventing heaving during freeze/thaw cycles.
If your irises are not blooming well, it may be due to 1) the rhizomes planted too deep—top of the rhizome should be at the soil surface, 2) being in too much shade – at least half a day of sun is needed, 3) overcrowded – dividing and re-setting rhizomes every 3-4 years may help, and 4) water drainage problems – bearded irises need well-drained soil or raised beds to perform best.
Public sale July 30
Interested in acquiring bearded irises (and other perennials, including daylilies) for your garden? An excellent place to find a very wide selection is the public sale and auction sponsored by the Lincoln Iris Society to be held Saturday. It's open to the public from 10 a.m. to 4 p.m., with an auction of newer varieties at 11 a.m., at the St. Andrews Lutheran Church, 1015 Lancaster Lane (4 blocks east of 70th & Vine, left onto East Avon, church is on the left). All of the irises and other perennials for sale are hardy in our part of the country. For more information contact Gary White at (402) 613-1159.