No matter the variety you choose to grow, there are a few things you can do to help your irises thrive in your garden. Follow these tips below for the healthiest blooms. Plant them in a sunny spot in late summer. The plants need well-drained soil and at least six hours of sunlight per day. A full day of sun is even better to keep the rhizomes dry. Prepare their beds. Use a low-nitrogen fertilizer and apply it twice a year: In early spring and just after bloom when the rhizomes are forming the next year's flowers. Only water if it's extremely dry or after transplanting. Give them room to breathe. Bearded iris need good air circulation. Plant them a minimum of 16 to 18 inches apart (less space for dwarf irises and more for tall bearded iris varieties). Do not mulch. Mulching helps the soil retain moisture, and too much moisture will cause the rhizomes to rot. Remove seedpods that form after the blooms have faded. This prevents seedlings from choking the surrounding soil. Seed formation also saps energy needed by the rhizomes, roots, and leaves. Prune back the foliage in the fall. This will reduce the chances of overwintering pests and diseases. Make dividing a habit. Divide clumps of bearded iris plants every three to four years in late summer.