If you grow beautiful irises in your garden, at some point, you will eventually have to determine the best time to transplant your irises. This is a normal process in properly caring for an iris as it grows larger and larger. Of course, knowing exactly when you should do this is key to maintaining beautiful, healthy plants.
As a whole, the best time to transplant your irises is in the hottest days of summer, from late July to early August. The transplantation is necessary in order to avoid overcrowding of your iris plants. Now, you might be wondering how you will know that the plant needs to be transplanted.
Take a good look at your irises growing in your garden. Observe their overall condition. If their blooms have decreased, it is a sure sign that you have to start transplanting. If the blooming has decreased in your irises, it is probably due to the flowers being overcrowded. Another indication is if the rhizomes begin to heave out of the soil. When irises overcrowd, their root systems will push up from under the ground.
To prepare for transplanting, dig up your iris plant with a spade, and pull the entire thing out if you can. Remove as much dirt as possible for the rhizomes, then divide them. Each rhizome can be divided into separate pieces in lengths of at least three or four inches. They should also have at least one set of leaves still on, and the roots intact.
Plant the divided iris rhizomes in a good, sunny location that has well-draining soil after trimming the leaf fans to six to nine inches. Try to space out each transplantation about 18 inches apart. Dig a deep enough hole to accommodate the rhizomes and cover them adequately with soil. Cover the roots over as well, and water the irises thoroughly for best results.