How to divide iris rhizomes

BBC Gardeners' World Magazine

Published: Wednesday, 24 April 2019 at 3:00 pm

Find out how to rejuvenate tired clumps of irises, in our practical guide.

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To do

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Irises can become congested over time, which tends to inhibit flowering. This can be remedied by lifting and dividing their rhizomes to give them a little more space. Wait until flowering is over before dividing the iris clump, discarding any old, woody rhizomes and replanting only young, healthy plants into freshly-prepared soil.

You Will Need

Irises
Garden fork
Knife
Trowel

Total time: 30 minutes

Step 1

Use a fork to dig up a congested clump of irises. Ease the plants from the soil, taking care not to spike the rhizomes.

Step 2

Pull the congested rhizomes apart by hand, or cut them with a knife. Choose healthy pieces with leaves and discard old, woody sections.

Step 3

Newly-planted rhizomes are vulnerable to wind rock, so it's a good idea to reduce the leaves by half. Use a sharp knife to trim them.

Step 4

Replant healthy rhizomes about 12cm apart with the leaves facing towards the sun. Make a shallow hole and half bury the rhizome, giving it a firm push to bed it in - they like to bake in the sun, so don't bury them too deep.

It's a good idea to lift and divide clumps of irises every three years.