When it comes to thinning your irises, timing is key. The ideal time to thin your irises is in September. This is because the plants are generally done flowering by this time and are entering a period of dormancy. Thinning your irises every two or three years is important to maintain their health and vigor.
To begin the thinning process, you will first need to prepare your irises for division. Start by cutting back the leaves to about one-third of their full height. This helps reduce stress on the plant and allows for easier handling during the division process. It’s important to note that cutting back the leaves should be done before digging up the rhizomes (roots).
Once the leaves have been cut back, it’s time to dig up the rhizomes. Carefully use a garden fork or shovel to loosen the soil around the clump of irises. Gently lift the clump out of the ground, being careful not to damage the rhizomes.
Next, you’ll want to separate the rhizomes. Look for any overcrowded or damaged rhizomes that need to be removed. These can be identified by their smaller size or any signs of rot or disease. Using a sharp knife or garden shears, carefully cut the rhizomes apart, making sure each division has a healthy portion of roots and a fan of leaves attached.
As you divide the rhizomes, it’s important to maintain their orientation. Each division should have a fan of leaves that is facing outward, away from the center of the clump. This ensures that each new plant will have access to sunlight and proper growth conditions.
Once the rhizomes have been divided, it’s time to replant them. Choose a location in your garden that receives full sun or partial shade. Irises prefer well-drained soil, so make sure the planting area has good drainage. Dig a hole wide and deep enough to accommodate the rhizome, making sure the top of the rhizome is level with the soil surface.
Place the rhizome in the hole, spreading out the roots and ensuring the fan of leaves is facing outward. Backfill the hole with soil, gently firming it around the roots. Water the newly planted rhizome thoroughly to ensure good soil contact and to help settle the plant in place.
Repeat this process for each division, spacing them about 12 to 18 inches apart to allow for proper growth and airflow. After planting, it’s important to continue watering regularly, especially during dry periods, to promote establishment and healthy growth.
Thinning your irises not only helps maintain their overall health and vigor but also allows for better air circulation and reduces the risk of disease. By dividing and replanting your irises every two or three years, you’ll ensure a beautiful and thriving display of these common man’s orchids in your garden.
