Tips for growing irises include planting them in an area with adequate sun and soil. This flowering perennial requires planting in well-drained soil in mid to late summer. They grow best in USDA Hardiness zones 3 to 9 because they need a dormant period to flower.
To prepare the garden bed, loosen the soil to a depth of about 12 to 15 inches and work in compost. Dig a hole 4 inches deep and 10 inches wide. Leave a small mound of soil in the middle and spread the rhizome roots over it. Plant irises in clusters of three, about 1 to 2 feet apart. Top dress with a low nitrogen fertilizer and water well.
Irises need at least six hours of sun each day and do not like shade. Make sure the iris bed is not overshadowed by other plants and that plenty or light and air can circulate. The rhizomes can be exposed because they need to breathe. After the flowers bloom, do not cut the remaining leaves. Allow them to die naturally.
Iris rhizomes are prone to rot so do not apply mulch or the bed may get too moist. Divide and transplant the rhizome clumps every two to five years to prevent overcrowding.