The Homeowners Column

The Homeowners Column

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Dividing and transplanting peonies

Photo of Sandra Mason

Sandra Mason
State Master Gardener Coordinator
slmason@illinois.edu

August is the month of weeding and watering. September activates a resurgence of garden activity, a hustle and bustle of dividing and moving perennial plants. All those plants you didn't get moved in the spring now get a second chance to sprout wheels. However, peonies are one of the few perennial flowers that survive better only as a September division.

Now as you were reading the paragraph above were you saying pennies, pieneys, pea-o'nees or pea'o-nees (my choice). Just say peony and your geographical origin becomes quickly apparent. To help us or to confuse us further, the genus is Paeonia and is pronounced pea-o'ni-ay.

We may not agree on the pronunciation, but we can agree on the splendor of peony flowers. Peonies are a common Midwestern plant found tucked into every old farm landscape. Their popularity grew out of their preponderance of blooms perfect as cut flowers for decorating graves on Memorial Day. Peony history goes back to cultivation in China over 2500 years ago. Through continued breeding programs peony popularity as a garden plant has blossomed to include hundreds of improved cultivars.

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So how often should peonies be divided? My answer - every 150 years without fail. If your daytime calendar doesn't go up that far, just keep in mind peonies do not require regular division for successful blooming the way other perennials such as bearded iris require.

However multiple reasons exist on why we would want to divide and transplant peonies. It's time to transplant when peonies exhibit a continued lack of flowers over several years. Often the cause is too much shade as trees grow to overtake what was once a sunny garden. Peonies are sun-lovers and without at least 6-8 hours of sun the plants may live, but do not thrive. Plants may also decline due to overly wet garden sites. Peonies appreciate well-drained soil with an abundance of organic matter. Also peonies are long-lived plants and producing multiple divisions is a great way to share grandma's peonies with other relatives.

To divide peonies grab a sharp spade and dig a trench around the plant about 8-10 inches away from the perimeter stems of the clump. Depending on how old the peony is the roots may be quite large and woody. To divide the clump use the spade or a heavy knife. Each root division should possess at least 3 to 5 "eyes". The "eyes" actually look more like pink "noses" and are the shoots for the next season. If the stems and leaves still look nice and green, do not cut them off the divisions.

The "eyes" should be planted about one to two inches deep and no deeper. If planted too deeply, the plant will produce foliage and no flowers. Plants should be spaced about 2 to 3 feet apart. Water well after planting. Remove stems once they turn yellow. Mulch with shredded bark or pine needles in early winter.

Peonies can suffer from fungal diseases. Peony measles is a fungal disease that causes purple spots on leaves, stems, flower buds and petals. The disease cannot be stopped this late in the season; however, sanitation is very important to control this disease as well as botrytis and phytopthora for next year. Remove and bury or actively compost the stems and foliage as soon as they die down this fall. Fungicide sprays in spring can also be used to prevent peony diseases.

Rediscover peonies as September is also the perfect time to plant new plants. By selecting early and late season peonies the flower period can be stretched to 6 weeks. Newer cultivars which have stouter, sturdier stems do not require staking and many show good disease resistance.

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Check out the peony garden at Allerton Park and Retreat Center in Monticello, Illinois to see which ones look great even without their spring bling of flowers.

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