Have your irises grown into huge clumps, but not produced blooms like they used to? Some clumps may also have started to lift out of the soil, which is an indication it’s time to divide and conquer.
Spring and summer blooming plants like daylilies, iris, daisies, and oriental poppies can be safely divided and transplanted from September until the ground freezes.
Lift clumps gently out of the soil with a garden fork. Pull or cut clumps apart, and discard shriveled, diseased or mushy bulbs in the trash. Even the best compost piles will not get hot enough to kill plant diseases.
Trim leaves to about 4-6 inches above the bulbs.
Replant bulbs 12″ to 24″ apart after refreshing the soil with an amendment such as EKO Compost. Remember in a few years these will also need dividing, so give them enough room.
Divide one color or type at a time or label each to avoid mixing them up while transplanting. Sometimes friends and neighbors will have clumps to trade, adding an exciting new variety to your landscape!
Dividing in the fall allows spring and summer blooming plants time to recover, grow new roots and save up energy. On the flip side, wait to divide fall-bloomers, like mums, asters and ornamental grasses, until the spring.
If you want more spring color, Fort Collins Nursery offers hundreds of varieties of bulbs starting in September. Stop in to check out all the color your garden needs!
Originally published on October 7th, 2010. Updated on April 30th, 2019.