FALCON HEIGHTS, Minn. — The end of August is a fantastic time for dividing perennials and Iris are one of those that benefit from division as the weather cools. Here’s how:
1. Choose the right time: Plan to divide your irises in the late summer to early fall, ideally four to six weeks before the first frost. This gives the plants time to establish roots before winter.
2. Prepare tools and area: Gather a spade or garden fork, a sharp knife, pruning shears, and a bucket of water. Clear the area around the irises to ensure you have easy access.
3. Dig up the clump: Carefully dig around the iris clump with a spade or garden fork, starting about 6 inches from the base to avoid damaging the rhizomes. Gently lift the clump out of the ground.
4. Separate the rhizomes: Shake off excess soil and inspect the rhizomes. Using a sharp knife, cut the rhizomes apart, ensuring each division has at least one fan of leaves and several healthy roots. Discard any old, diseased, or damaged rhizomes.
5. Trim the leaves and roots: Cut the leaves back to about 6 inches in length to reduce water loss and stress on the plant. Trim the roots slightly if they are too long or tangled.
6. Prepare the planting area: Choose a sunny location with well-draining soil. Amend the soil with compost if necessary to improve fertility and drainage.
7. Plant the divisions: Dig a shallow hole or trench and place each rhizome horizontally with the roots spread out. Ensure the top of the rhizome sits at the soil surface with some of the rhizome showing. Space the divisions about 12 to 18 inches apart to allow for growth.
8. Water and mulch: Water the newly planted irises thoroughly to help them settle in. Apply a thin layer of mulch around the plants to retain moisture and regulate soil temperature, but avoid covering the rhizomes.
9. Monitor and maintain: Keep the soil consistently moist but not waterlogged until the plants are established. Remove any weeds that may compete for nutrients and monitor for pests or diseases.
10. Enjoy blooms: With proper care, your divided irises should bloom beautifully in the upcoming seasons, adding vibrant color and charm to your garden.
Be sure to stop by the Minnesota Horticultural Society Booth during the rest of the Minnesota State Fair to ask questions and take in a demonstration or two!
You’ll find them in the Dirt wing of the Ag-Hort Building.