August is a great time for dividing perennial plants to expand your garden. Irises and daylilies can be divided now. If your Siberian irises have stopped blooming then they are definitely in need of division.
Dividing Iris – If you have 20 fans, it’s time to divide
- Cut back the leaves or fans by half.
- Irises grow from “rhizomes” which are just under the soil close to the surface. Dig up the whole clump, not just the piece you’re transplanting. Shake off the soil or even wash it off, as you want to be able to really see the whole plant.
- Cut the plant apart with a sharp knife making sure that each section has between 1 and 3 good stems (3 is best). It’s inevitable that some roots will be lost, but be as gentle as possible when separating rhizomes.
- Cut the leaves back by 2/3’s. Then cut the leaves on the outside in a sloping manner so your foliage looks like a fan.
- To transplant, dig a hole that has a mound in the middle so you can place the rhizome on the mound and roots will lay down the sides of it.
- Plant the new rhizomes at least 1 ft. apart.
- The top of the mound should be very near the soil surface as iris rhizomes sit very close to the surface. Fill in the soil around the roots and rhizome.
- Water in just as you would a new planting. Continue to water several times a week.
- When dividing a daylily, the entire plant doesn’t need to be lifted from the ground.
- Cut down through the plant with a sharp spade or knife making 2 or 3 sections from the plant. Make certain each section has several leaves and stems.
- Dig out the sections that are to be moved using a shovel. Don’t bother to remove attached soil as you can immediately move the smaller plant to its new site.
- Soil should be filled in around the original daylily.
- Plant new divisions at same ground level as the original plant and water in well.
- Continue to water several times a week as you would with a new plant.