Gardening Tips and Highlights

Dividing and transplanting Iris

by Christine Yesko


This is the best time to divide and transplant Iris, and here is how you do it.

Bearded Iris grow from rhizomes on the surface of the soil and can get crowded as time goes on. They benefit from dividing every few years. Later summer is the best time to do this. Regular dividing will help keep It is flowering profusely and help prevent problems with Iris borer and soft rot. It is best to do this by the end of summer so the replanted rhizomes can become established before the onset of winter.

If the soil is dry, water a couple of days prior to dividing. Lift clumps carefully with a shovel or a pitchfork. Shake the loose soil off the roots or rinse with a hose, if necessary. Separate individual rhizomes by gently pulling apart tangled sections. Inspect rhizomes for signs of Iris borer damage and soft spots from disease.

If the plants have dark streaks on the flower leaves, there is likely Iris borer damage. Uses a clean, sharp knife to cut away damaged areas. Remove damaged leaves and then cut the remaining leaves back to four to six inches long. Then, cut the rhizomes apart at their natural division, about three inches long, making sure there is a fan of leaves and healthy root growing from each piece.

Replant in any area of the garden at about a 12-inch spacing. Position the rhizomes so the fan of leaves is placed in the direction you want the plant to expand. Also, be sure to leave the top of the rhizome slightly exposed. If they are planted too deep, they become much more susceptible to infect and may reduce the flowering. Water the area thoroughly and be sure to provide extra water until the plants are established. It is are not heavy feeders, and should not require any fertilizer at planting time. Bone meal can be sprinkled in the planting hole, if desired. This will help with root formation.


Even after dividing, they should bloom next spring without missing a beat.