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If I could have just one shrub in the garden, it would be a peony. They’re tough, beautiful and oh-so-easy to grow.

When I was young, I thought of them as a “grandma flower,” an old-fashioned perennial that had its heyday in the first half of the past century. But I saw peonies everywhere, in gardens and even abandoned farmsteads and neglected cemeteries. One of my earliest flower memories is of bending over a neighbor’s pink peony, not to marvel at its impressive flowers, but to watch ants swarm over the sticky flower buds.

Peonies never fell out of favor in Minnesota and Wisconsin, which have the cold winters the plants need. Some of the nation’s premier peony nurseries are right in our area. While it’s too late to order peony roots for planting this fall, now and into early October is the time for gardeners to divide their own peonies to share these gorgeous plants with friends and neighbors.

First, some facts about peonies:

• The plants we grow today have their roots in Asia, around the Mediterranean and even parts of North America. The Chinese were cultivating peonies more than 1,000 years ago, and peonies are a feature of classical Chinese painting.

• Peonies are one of our longest lived perennials. Individual plants can live to be more than 100 years old.

• Contrary to legend, ants gravitate to peony buds for the sap, not to help the flower buds open. If there were no ants, peonies would still flower.

Today’s peony enthusiasts have more choices in flower and plant form than ever before. In addition to the classic ruffled-ball herbaceous peony with masses of petals that I remember from childhood, there are peonies that have flowers with single petals, double petals, semidouble petals and big clusters of colorful stamens at the flower’s center. Tree peonies mature into 4-foot shrubs that remain standing through the winter, and showy intersectional or Itoh hybrids have huge flowers and dense, disease-resistant foliage that looks good all summer.

Newer varieties tend to have stronger stems and big flowers in colors such as bright yellow and lavender, but often don’t have the delicious spicy smell of many herbaceous peonies that were bred before 1960.

Unlike most perennials, peonies that are growing in a good location don’t need to be divided. But a mature plant can easily be dug up, divided and shared, and now’s the time to do it.

You’ll need pruners as well as a sharp knife to divide roots. Prune the leaves and stems back to the ground — you should do this in the fall anyway to peonies, except for tree peonies — and dig out as much of the root system out as you can. The roots will be big. Dig in a circle as big as the plant was wide, and gently pry the root clump from the ground.

The plant will be easier to divide if you spray the roots with water and wash off soil so you can see what you’re doing. In the fall, peonies set “eyes” that provide next spring’s growth, so you’ll see white or pink bumps high on the roots. The goal is to divide the plant so that there are three to five eyes per division, creating a strong plant that will pop up in the spring.

Cutting rather than prying the roots apart will give you better divisions. Remove any roots that are soft or diseased.

Although peonies are nearly carefree plants, they are persnickety about two things: sun and planting depth. Most peonies do best in full sun; flowers will be fewer and smaller in shade. (Tree peonies prefer partial shade.) The eyes on a peony division should be no more than 2 inches below the surface of the soil. Planted deeper, the plants may refuse to flower.

Water newly planted divisions, and mulch them the first winter with leaves or straw to help them through the cold. Since you won’t be able to see any sign of the new plant above ground, mark the spot so you don’t dig there by mistake while planting bulbs or doing other chores in the garden.

The following spring, new plants may be small and might not flower the first year. But sometimes we get lucky. I’ve had newly planted peonies throw up to three flowers in their first growing season.

Planted correctly, there’s no need to ever touch a peony again. If growing conditions are good, the plants are quite happy being left alone. But it’s a delight to share a treasured plant with friends.

A detailed video on dividing peonies can be seen here: finegardening.com/article/how-to-divide-peonies

If you prefer to buy peonies, you’ll find plenty of plants in garden centers in the spring. If you’d rather order specific varieties for planting next year, there are plenty of websites to look at and ponder over. Here’s a list of local peony growers from the Minnesota Peony Society, with links to their web pages: mnpeony.org/peony-growers.

Mary Jane Smetanka is a Minneapolis freelance writer and Hennepin County master gardener.