The typical rule of thumb is, that if a plant blooms in spring or summer, divide it in the fall, and divide fall blooming plants in the spring. The reasoning behind this is that when a plant is not in flower, its energy will go into new root and foliage formation rather than into making flowers. As soon as the growing tips of the plant appear in the spring, division may be made.

When dividing plants in the spring, be sure to allow enough time for the roots to become established before hot weather arrives. Expect perennial plants that are divided in the spring to bloom a bit later than usual.

Another tip is to remember that the center of the plant being divided is the oldest, and will not perform as well as the newer, outer growth. New divisions should include at least 3 growing points and a good-sized healthy root system. Dispose of any old, diseased or damaged plant portions.

When replanting new divisions, make certain planting depth is at the same level as when the plant was lifted from the ground. Mulch may be applied around new transplants to help keep soil moist and also to keep weed seeds from germinating. Keep mulch away from stems and apply 2 to 3 inches deep.

Did you know? If you have no room for additional plants in your garden, any extra divisions may be given to friends or neighbors. Another option is to donate your extra plants to a local garden club or other organization for their annual spring plant sale. Monies received from these plant sales are often used for student scholarships or community betterment projects.

Questions? Contact McCormick at yvonne@iastate.edu for information or advice.

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