When is the best time to transplant irises?

The best time to transplant irises is in July, August or September. Irises should be transplanted to locations that receive six to eight hours of full sun per day. The soil should be well drained and slightly acidic.

Dig up the entire clump of irises, shake off the dirt and divide the rhizomes in the clump. The largest rhizomes should be transplanted, and the older rhizomes in the center of the clump should be discarded. Plant the rhizomes 12 to 24 inches apart at soil level or slightly below, with the roots spread out and facing down. If planted closer together, the irises need to be thinned out every two to three years.