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Dividing Perennials

Mid-September through early October is the preferred time to lift and divide many perennial flowers, particularly spring and summer-blooming perennials like peonies, iris, bleeding heart, hosta and coralbells. If divided in the fall, they'll still have time to re-establish before blooming next spring. If divided in spring, on the other hand, they may not bloom well until the following year.

Use a sharp garden spade to lift your perennials. Dig several inches out from the outer-most stems, and lift the clump out of the ground. Then, divide the clump into sections. With peonies, cut the root clump into sections that have at least three or four eyes. Use a sharp knife. Be sure to leave one of the long roots attached to each piece that has an eye on it. Don't divide peonies more often than once every three years.

Iris should be divided every four years or so. Lift the clump out of the ground and cut the leaves back to about six inches. Dividing the clump depends on how tough the roots are. but however you divide it, try to damage the fewest roots possible.

How deep you replant the divisions is also important. Plant peonies and iris so the top of the root or rhizome is no more than two inches below ground level. If you plant them too deep, especially peonies, they may not flower. Adding a handful or two of bone meal to the planting hole will help your divisions re-establish better. It is also a good idea to sprinkle a little fertilizer on the soil surface after filling the soil back in the planting hole. This will slowly work its way into the root area.

If you have further questions, please contact your local county extension office for further information.

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