Bearded irises are a beautiful addition to any sun garden. They command one of the most extensive color palettes in the entire flower kingdom, with each hue as vibrant and striking as the next. They bloom in late spring to early summer, while reblooming varieties add a second flower period sometime between midsummer and the first frost.
Here are five keys to getting the most out of your bearded irises:
- Plant them where they will receive at least five hours of sunlight daily. Blooms will be smaller and less colorful if they receive too much shade. Direct sunlight brings out the best in bearded irises, although you should be vigilant about watching for signs of dehydration. Irrigate the plants whenever the soil appears to be drying up.
- Make sure the soil is fertile and well drained. Although bearded irises do well in most garden soils, try improving the earth for optimum results. Prepare the planting site by removing all debris and weeds, then spade or rototill it to a depth of 12–15 inches (30-38 cm.). Mix in a generous, 2- to 4-inch (5-10 cm.) layer of dehydrated manure, garden compost or peat moss, and finally add a slow-release blend of plant fertilizers such as Breck’s Food for Bulbs and Perennials. If the soil is already rich, well-drained loam, adding fertilizer will help ensure superior growth and blooming. It’s also recommended that you fertilize a second time, right after the blooms open.
- Don’t let your irises be crowded by neighboring plants—or each other. When planting, allow at least 12 inches (30 cm.) between each iris rhizome as well as between rhizomes and other plants. Rhizomes need plenty of sunshine and air; otherwise, they may fail. Dig shallow holes 10 inches (25 cm.) across and 2-4 inches (5-10 cm.) deep. Make a ridge of soil down the middle of each hole, dividing it in half. Place a rhizome on the ridge, spreading roots to both sides. Cover with soil and firm with your hands. In clay soil, rhizome tops should be slightly exposed; in sandy soil, cover them with an inch of soil. Water thoroughly.
- Remove spent blooms consistently. This will help promote further blooming from remaining buds, which are spaced along the stems. After all the blooming ends, cut the stems down at the base to discourage rhizomes from rotting. Trim away any brown leaf tips but don’t cut off entire leaves while they are green because they are undergoing photosynthesis to prepare for next year’s growth. Following the first hard frost, prune back yellow or spotted foliage and remove any debris on the ground at the base of the plants.
- Divide and replant them every 3–5 years. While this rejuvenates bearded irises, beardless varieties don’t take well to it and often fail to flower the season following their move. You can divide your bearded irises after they’ve finished blooming, but make sure you’ve prepared the site for replanting the divisions before digging out the clumps. Make clean cuts and be careful not to damage roots while digging. Remove any infected parts you come across. Make a note to irrigate thoroughly after you’ve replanted the irises.