Dakota Gardener: Divide and conquer your garden

"You'll never guess what I found behind the shed ... another peony," I shouted to my husband. This makes the tenth peony we have found in a random location around our backyard. Considering the peony is growing right next to my compost bin, I am not planning on keeping it there. Add that to the lilies I found along the fence line, the iris in the middle of the yard and the surprise tulips that popped up this spring in the front of the house, I have enough flowers to fill in some of the bare spots in my landscaping.

Now is a great time to do the landscape facelift I have been itching to work on all summer. The garden is maintaining a steady production of vegetables and most of the spring and summer flowering plants have already bloomed. It's time to conquer the plants that will be divided or moved; this will give them the time needed to settle into their new location before the first frost comes.

Why divide perennials? Plants can get overcrowded in a flower bed, decreasing the airflow through the plants. Decreased airflow leads to diseases such as powdery mildew or rust fungi. Dividing perennials will prevent them from overtaking an area of your landscape. Dividing plants also reduces competition for nutrients in the soil. Reducing competition promotes more growth and more blooms. Some flowers, like iris, will not bloom as often if overcrowded.

Dividing plants is simple. Water the soil deeply the day before dividing to loosen the soil and give the plant enough moisture to withstand transplanting. If possible, divide on cool, cloudy days to prevent the plants from drying out. Use a spade or a sharp knife to dig up the plant, then either loosen the roots and gently pull the plant apart or cut the plant with a clean, sharp knife or spade. Aim to have at least three vigorous shoots on each division. Place the divided plant into a moist, shaded area until ready to replant. If you are dividing a plant with a rhizome, such as an iris, cut the rhizome into 3 to 4-inch sections with a clean, sharp knife.

Common perennials that can be divided in the fall include peonies, iris, lilies and salvia. As a rule of thumb, spring- and summer-blooming perennials should be divided in the fall, and fall-blooming perennials in the spring.

Some plants need to be divided more often than others. For instance, alliums should be divided more often than blanket flowers.

Other plants do not respond well to division. Balloon flower, for example, do not like to be disturbed and will not bloom for a few years after division. Their roots are also brittle and should be handled carefully if dividing. For more information about how and when to divide perennials, visit the University of Minnesota Extension's guide on how and when to divide perennials at https://extension.umn.edu/planting-and-growing-guides/dividing-perennials.

As for my large collection of randomly found peonies, I've been giving them to friends as an easy perennial for their landscapes. Though I don't need or really want them, it is still exciting to find a random peony in my yard and wonder how or why it's there.

For more information about gardening, contact your local NDSU Extension agent. Find the Extension office for your county at ndsu.ag/countyoffice.