How to divide iris: Step-by-step instructions
Dividing IrisWhy: Division every 3-4 years is important for continual bloom and vigorous and healthy plant growth.
1) Dig up the entire clump with a garden fork or split off individual rhizomes. Try to avoid damaging the roots or the leaves.
2) Remove excess dirt and dead material from the clump. Remove enough so that the clump is fully exposed.
3) Trim the leaves down to 4-6”. Trim in at an angle on each side.
4) Break apart the rhizomes from the clump by using your hands or a knife.
5) Discard any rhizomes that are spongy, rotten, or have visible insect damage.
6) If necessary amend the soil of the planting location with bone meal or compost. So long as the soil is light your iris should do fine.
7) Replant rhizomes so that the top of the rhizome is visible and flush with the soil.
8) Pack firmly and water moderately.
Things to Keep In Mind:
1) Be sure to mark with a permanent marker or paint pen the name or description of the cultivar for reference on the fan of the iris.
2) If storing rhizomes be sure to save in a cool, dry location. Iris can survive several months out of ground if properly stored.
3) It isn't necessary to soak or wash rhizomes free of dirt if you are just moving them around the garden. Only wash or soak rhizomes if the rhizome is infected with rot or some other "bad thing". (Rot worksheet to follow!)
4) Importantly...put something back into your soil if it has been a while since you have divided. Iris will often use everything they can get from the soil. I recommend adding compost or a mixture of N-P-K to help get your iris off to a good start again.