Bearded Irises are a beautiful addition to any garden and they are easy to grow. For best results, plant iris rhizomes in late summer. This is also the best time to divide and replant existing iris plantings that have become overcrowded or failed to bloom in the spring. When planting new iris rhizomes it is important for the roots to get established before the end of the growing season so plant your iris at least four to six weeks before your first hard freeze or killing frost.
Iris need at least half a day of sun to promote flowering and should not be shaded by other plants. Make sure to loosen the soil to a depth of 12 to 15 inches and then mix in a 2 to 4-inch layer of compost. Irises need soil that is neutral to slightly acidic. If your soil is too acidic, add some lime.
Bearded irises have rhizomes (fleshy roots) that need to be partially exposed, or thinly covered with soil in hot climates. You can plant iris rhizomes by themselves but they look best planted 1 to 2 feet apart in groups of three.
Dig a hole approximately 10 inches wide and 4 inches deep. Build a small mound of soil in the middle of the planting hole. Center the rhizome on the soil mound and spread out the roots on either side. Firm the soil around the roots. Newly planted rhizomes should be watered thoroughly.
Remember: Irises are perennials and require time to grow. You should notice new growth from the center leaf within 2-3 weeks of planting.