German irises can be propagated by dividing their rhizomes every few years. This process is called asexual propagation.
When to divideĀ
- Divide in late summer, after the irises have finished flowering.
- This allows the plants to become well-established and store carbohydrates.
- Irises divided in late summer are more likely to flower the following spring.
How to divideĀ
- Use a garden fork to dig up the iris clump.
- Shake off loose dirt.
- Pull the rhizomes apart by hand.
- Discard the old, woody center section.
- Select young, healthy rhizomes with at least one fan of leaves.
- Cut the rhizomes into pieces with a sharp knife.
- Trim the leaves by about half.
- Replant the rhizomes in fresh soil.
How to replantĀ
- Space the rhizomes 12ā24 inches apart.
- Plant them in a shallow hole, with the leaves facing the sun.
- Firm the soil around the roots, but leave the top of the rhizome exposed.
- Water thoroughly.
Why divide
- Dividing irises increases the number of blooms and reduces the risk of disease.Ā
Over time, irises can become congested, which can inhibit flowering.