Planting and Care for Bearded Iris
Bearded irises are one of the most beautiful heirloom flowers a gardener can grow. Their blooms are elegant and regal, their sweet fragrance is reminiscent of grape soda or root beer, and their ability to multiply rapidly has made them the ultimate “pass-along” plant. Ask any gardener where they acquired their lovely stand of purple irises and you’ll be greeted with tales of grandma’s colorful cottage garden, neighbors sharing handfuls of rhizomes over the garden gate, or a prized collection dug up and brought over from past homes.
Having success with bearded irises begins at planting time. The plants are grown from fleshy roots (called rhizomes) and the best time to plant them is from midsummer through early fall. Bearded irises need at least 6 weeks to develop a strong root system before the first hard frost.
Plant your iris in a sunny spot. Full sun is best, but they will need at least 6 hours of sun to produce a good show of flowers. Well-draining soil is also important. Heavy soil that is poorly drained can invite disease problems.
Plant at the Correct Depth
Iris rhizomes should be planted at or just barely below the surface of the soil. After planting, you should still be able to see the very top of the rhizome. Planting too deeply can result in rot and no flower production.
Dig a hole about 4 inches deep, and then build up a small mound of soil in the center of the planting hole. Position the rhizome on top of the soil mound and spread out the roots on either side. In very hot climates, you can cover the rhizome with 1 inch of soil to protect it from extreme heat. Firm the soil tightly around the roots, remembering to leave the top of the rhizome slightly exposed
Give the Plants Room to Multiply
Space the rhizomes 12-24 inches apart. The tighter the spacing, the sooner plants will grow together and need to be divided. If you want an immediate and abundant floral show, plant rhizomes 12 inches apart. If you prefer to divide your irises less often, use the wider spacing.
Newly planted rhizomes should be watered thoroughly, but unlike other plants they should not be mulched. Keep the area free of weeds and debris to ensure a healthy stand of gorgeous irises come spring.
Divide as Needed
Bearded irises usually need to be divided every 3-5 years to maintain good health and abundant flowering. The best time to divide them is between midsummer (at least 5-6 weeks after the plants have bloomed) and early fall.
Start by digging up a good-size clump of plants. Put them on a tarp and gently pull apart the roots until you have individual rhizomes with one to three sets of leaves attached. Discard the old, spent rhizomes from the center of the clump, and keep the healthy outer rhizomes for replanting. Trim the leaves down to about 6” to reduce stress on the transplant. Then replant just as you would a new rhizome.
Enjoy a Lifetime of Beautiful Blooms
It’s easy to see why bearded irises are considered the ultimate “pass-along” plants. Their ability to multiply and thrive for generations is truly unmatched. Bearded irises give us elegant blooms, rich fragrance, and timeless beauty. They also give us stories to treasure among family, friends, and neighbors.
To learn more about gardening with perennials, you may be interested in reading: How to Select Perennials for All Season Color, 10 Easy Perennials for Sunny Gardens, and How to Design a Fragrant Garden.