Gardening Help FAQs

Here are answers to some of the most common questions we receive about garden plants. You will find concise information on general gardening techniques as well as plant selection and care. For detailed information on specific plant pests and problems refer to our Common Garden Pests and Problems page.

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Horticulture Questions and Answers

When and how should I divide my perennials?

Late July through September is the preferred time to lift and divide many perennial flowers. This includes spring and early summer blooming perennials such as iris, peonies, hostas, bleeding hearts, and coral bells. This will give them a chance to develop a good root system before cold weather sets in. Given proper care, they should also bloom the following spring, but some will take two years to bloom well.

To dig, use a sharp garden spade to lift your perennials. Dig several inches out from the outermost stems and lift the clump out of the ground. Using an old, large knife, cut the clumps into sections. Another method is to use two digging forks and pry the clump apart.

When replanting peonies, work a bucket full of compost into the soil in the planting hole and plant each clump about 18 inches apart. Each clump should have 3-4 eyes. Plant so that the eyes are no more than one to two inches below the soil. If you plant peonies too deeply, they may not bloom. Remove and discard the old foliage to reduce the spread of disease. Peonies do not need dividing on a regular basis. If they are flowering well, leave them alone unless you want to increase your number of plants or relocate a plant.

Bearded iris and perennial asters should be divided every three to four years. Divide the clumps keeping only the young, healthiest rhizomes. Discard the old rhizomes in the center of the clump. Dust any cut part of the rhizome with sulfur powder and replant. Spread the roots out and make sure the rhizomes are slightly above ground. Do not cover them completely with soil. Before planting, work the soil well and be sure to incorporate some superphosphate into the planting holes, but keep it off the rhizome itself. After planting, water the area well to promote root growth.

Hostas, bleeding hearts, and coral bells may also be propagated at this time. Cut the clumps into two to four clumps, depending upon size, and replant at the same depth in well prepared planting holes which have had ample compost or peat moss added.