When do i divide iris

New growth may be noticeable within two to three weeks and begins with a new center leaf in the fan. Leaves carry on photosynthesis for next year's growth. Don't trim iris leaves until fall. Only snip brown tips and cut the flowering stalk to the ground at a slant to discourage rot. This will reduce the chance of overwintering pests. Break off seedpods that form after the blooms have faded. Seed formation saps energy needed by the rhizomes, roots, and leaves.

Keep your iris beds free of weeds and fallen leaves so the rhizomes may bask in the sun. Don't be afraid to divide your rhizomes. Dividing will multiply your iris to give to friends or barter with gardening pals. Remember your supply is always growing. Let's Stay Connected. By entering your email, you consent to receive communications from Penn State Extension.

View our privacy policy. Thank you for your submission! Home Dividing Irises. Dividing Irises. Dividing irises is good for the plants and will result in irises to give away to friends or increase the display in your garden. Photo credit: Albert Dezetter from Pixabay. This may occur in as little as two years or as many as five. Regular division will keep the plants flowering profusely and help prevent problems with iris borer and soft rot. Bearded iris can be divided any time after flowering; this is often done in July or August in the Midwest so the replanted portions will have plenty of time to develop new roots and become established before freezing weather arrives.

Lift clumps carefully to avoid damaging the rhizomes. Lift clumps of iris carefully using a shovel or pitch fork. If the soil is dry, water the bed thoroughly a day or so beforehand to make digging easier. The heavy, but shallow-rooted rhizomes are generally easy to see, making it fairly easy to avoid injuring the rhizomes when digging.

If possible, lift the entire clump as a whole rather than breaking it up. Shake off the loose soil from the clumps. If your garden soil is fairly loose, you should be able to get most of the soil off the roots, but you can rinse off any remaining soil with a garden hose if necessary. Separate lifted rhizomes by pulling them apart. Separate individual rhizomes by pulling apart tangled sections. Inspect the rhizomes carefully for signs of iris borer damage and soft spots from disease.

If the plants had dark streaks on the leaves, then the rhizomes likely are infested with borers. The female borer moth lays its eggs on the leaves in the fall and the young caterpillars tunnel down the leaves to get to the rhizomes, leaving tell-tale streaks behind on the leaves. The plump, pink mature caterpillars generally leave the rhizomes in August to pupate in the soil.

Dividing bearded iris. Quick facts. Suitable for Bearded irises with rhizomes fleshy stems at soil level , plus clump forming herbaceous irises Timing Mid-late summer for rhizomatous irises; autumn or spring for clump-forming irises Difficulty Moderate. Jump to Suitable for When to divide irises How to divide irises Problems. Suitable for When to divide irises Rhizomatous irises having fleshy stems at soil level are divided just after flowering Clump forming irises are divided in early autumn or early spring.

Lift and divide rhizomatous bearded irises every three to five years This is ideally carried out six weeks after flowering, to give sufficient time for the plants to produce new growth for the following season before they enter winter dormancy Division: Cut away each fan of leaves from the clump, using a sharp knife. Divide large clumps shortly after flowering, using two forks inserted back to back in the centre of the lifted clump Remove any old rhizomes and roots; avoid breaking the clump into small sections Replant the younger outer sections to the same depth as they were planted before Unguicularis irises Iris unguicularis are low-growing clump-forming irises with beardless flowers that flower in late winter and early spring.

Divide clumps in autumn, or wait until after flowering has finished in spring Use your hands to pull apart the divisions, or, if this is insufficient, try two hand forks inserted back-to-back in the centre of the lifted clump Split the clump into largish sections to avoid disturbing the roots excessively Replant the divisions to the same depth as they were planted before Pacific Coast irises Pacific coast irises are low-growing clump forming irises with beardless flowers and grass-like leaves.

As these irises dislike root disturbance, lift only part of the clump in autumn the best time or in late spring once new roots have appeared Take divisions from the healthy and vigorous areas at the edge of the clump, replanting them to the same depth as they were planted previously.

Problems Those irises divided and re-planted in summer are at risk of drought during dry spells Watering the area and allowing it to drain overnight before planting, then watering every five days during dry periods after planting, can help in these conditions.

See also 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.

Use a fork to dig up a congested clump of irises. Ease the plants from the soil, taking care not to spike the rhizomes. Pull the congested rhizomes apart by hand, or cut them with a knife.

Choose healthy pieces with leaves and discard old, woody sections.