Apply a thin layer of compost around the base of plants each spring, leaving the rhizome (fleshy root) exposed. As flowers fade, cut back the flower stalks to the base of the plant. To encourage a second bloom on reblooming varieties, promptly remove faded flowers and maintain consistent watering throughout the summer. In autumn, trim away dead foliage and prune back healthy leaves to a height of 4 to 5 inches. Once the soil has frozen, apply a layer of mulch to help prevent roots from heaving out of the soil during alternate freezing and thawing. If heaving occurs, don't try to force plants back into the soil. Instead, cover rhizomes and exposed roots with soil. Divide bearded iris every 4 to 5 years, preferably in late summer. Each division should have one or two leaf fans. Older rhizomes that have few white feeding roots should be discarded.