How to Divide Bearded Iris in 6 Simple Steps

Dividing bearded iris every few years helps rejuvenate the plant and give you more flowers.

dividing bearded iris break rhizomes apart
Photo: Peter Krumhardt

Bearded iris grows from a thick, rootlike structure called a rhizome. As the plant matures, the rhizome multiplies, resulting in more leaves and flowers. But over time, the original rhizome withers and dies off, which can slow how quickly the plant produces new blooms. When this happens, it's necessary to divide the plant by removing and replanting the newer rhizomes so they have the space they need to fully develop. After dividing your bearded iris, it's easy to add the divisions to other parts of your garden, and share with friends.

What You'll Need

Equipment / Tools

  • 1 Garden fork or spade
  • 1 Pocket knife
  • 1 Pruning shears
  • 1 Bucket


Bearded iris should be divided in the late summer when the weather starts to cool. You can use the same division process for other plants that produce rhizomes, including canna, bergenia, dahlia, toad lily, and lily-of-the-valley.

  1. Dig Up Clumps

    dividing bearded iris digging with a red garden fork
    Peter Krumhardt

    Carefully dig the clumps with a garden fork or spade, taking care not to chop into the rhizomes more than necessary.

  2. Break Apart Rhizomes

    dividing bearded iris break rhizomes apart on roots
    Peter Krumhardt

    Divide the rhizomes by pulling them apart with your hands. In some cases, you might need a sharp blade such as a pocket knife to separate the smaller rhizomes from the main one. If so, dip your knife into a 10-percent bleach/water solution between cuts, so you don't spread any diseases to new rhizomes.

    A good rhizome will be about as thick as your thumb, have healthy roots, and have one or two leaf fans. Large, old rhizomes that have no leaf fans can be tossed out.

  3. Rinse and Evaluate Rhizomes

    dividing bearded iris washing roots in garden bin
    Peter Krumhardt

    In a bucket, wash the soil off the rhizomes so you can inspect each one for iris borer (a plump, white worm). If you find a borer, destroy it. Some gardeners like to wash their iris rhizomes in a 10-percent bleach solution to protect against disease, but that won't help plants that are already rotting. Make sure to discard any soft, smelly rhizomes you find and any that feel lightweight or hollow or look dead, like the rhizome shown above.

  4. Trim Leaves

    dividing bearded iris cutting fan of leaves with shears
    Peter Krumhardt

    With clean pruning shears, clip off the leaf blades to 4 to 6 inches long. This reduces the stress that the plant goes through as it concentrates on regrowing new roots instead of trying to maintain long leaves.

  5. Plant Divisions

    dividing bearded iris replanting rhizome division by gloved hand into soil
    Peter Krumhardt

    With your hands or a spade, dig a shallow planting hole. Replant divisions, setting the rhizome higher in the planting hole than the fine roots, which should be fanned out. A bit of the top surface of the rhizome should be just visible at the soil surface.

  6. Plant Remaining Rhizomes and Water

    dividing bearded iris completed planting
    Peter Krumhardt

    Space the plants 12 to 18 inches apart (closer for dwarf varieties, farther apart for the largest). Plant the rhizomes so the fan of leaves faces the same direction for the best display. Water well when planting bearded iris rhizomes, but don't continue to water unless the weather becomes dry.

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