What Peonies Need in October – 6 Easy Tasks to Prepare for Winter and Ensure Fabulous Spring Blooms

I love peonies, but that isn’t something I announce very often among gardeners. It’s a little like saying “I love cheese” in France. Everyone loves cheese in France, and the vast majority of gardeners adore these large, plush flowers with their abundance of tissue-paper petals. That’s why a peony is called the queen of the flowers.

Are peonies drought-tolerant and the kind of plant that thrives on neglect? Not at all, but fans insist that their dramatic, over-the-top, lush beauty makes it all worthwhile. October is a key time for peony care – and I am here to give you the scoop.

Keep in mind that these glorious flowers come in three separate varieties: herbaceous, intersectional, and tree peonies. The steps you need to take in October will depend on which of the three types you have in your landscape.

1. Cutting Back Herbaceous and Itoh Peonies

Of the three types of peonies, herbaceous peonies are the most common in home gardens. Their stems are not woody; they grow in spring and die back each winter. Itoh peonies, also called intersectional peonies, are hybrids, offering bigger flowers, stronger stems, and a longer growing season than herbaceous peonies. However, they also die back in autumn.

Cutting back your herbaceous and Itoh peonies is an important chore for October, but don’t jump the gun. As long as the peony leaves are green, they still are feeding the peony roots. Don’t cut them back until your area experiences a hard freeze. You will know because the foliage will turn yellow or brown. Once that happens, cut them back to some 2 inches (5 cm) above the soil. I like to use Fiskars Bypass Pruning Shears, available from Amazon, for this task because they make clean cuts that are less likely to damage dormant buds.

Once the peonies have been trimmed back, it’s clean-up time. Pick up all the messy pieces and toss them in the trash. Don’t think of dumping the debris into the compost pile. Overwintering there can cause fungal or mold issues.

2. Pruning Tree Peonies

Unlike herbaceous varieties, tree peonies have woody branches that stay in the garden all year. Their flowers are larger than herbaceous peonies' blooms, and they flower earlier in the season.

The most critical rule when it comes to pruning tree peonies is: DO NOT EVER cut them back to the ground. Leave the woody stems and branches alone. Snipping off woody branches will reduce (or eliminate) next year's flower buds. October is not the time to do heavy pruning – wait for late winter.

On the other hand, you should trim off the mature seed pods in October. You’ll recognize them because they are leathery. Also clip off dead or dying brown leaves. While you clear these away, take the time to pick up other fallen leaves and plant debris from the base of the plant to prevent fungal issues.

If your tree peony struggled with fungal issues this year, thorough cleanup is your first line of defense. Then, in spring, consider applying a preventative copper fungicide, like Bonide Captain Jack's Copper Fungicide, as new growth emerges to help protect fresh foliage.

3. Divide or Move Established Peonies

October is a great time to divide or transplant peonies if the plants are crowded or are currently growing in shade. If you move plants in the fall, they will have enough time to establish roots sufficiently to bear spring blooms.

Whether you are dividing or transplanting, the first step is to dig up the plant. A narrow perennial spade makes the job easier, especially when working around established plants. The Radius Garden Root Slayer Perennial Shovel, available from Home Depot, has a serrated blade that helps cut through tough soil and roots, making it particularly useful for dividing mature clumps. Work carefully around the peony to preserve as much of its root system as possible.

To divide peonies, dig up a clump of roots with healthy stems and leaves attached, then separate it from the main plant with a sharp knife or perennial spade. Each division should have at least three buds; they will grow into next year’s shoots. Plant each division about one inch (2.5 cm) deep.

4. Water Newly Planted or Transplanted Peonies

All newly planted peonies need a deep, thorough watering right after planting. This includes both new bare-root plants and all transplanted peonies. After that, water them weekly, or twice a week during dry periods, unless it rains. The soil should be moist, not wet. If you're unsure when to water, a Yamron 4-in-1 Soil Moisture Meter, available on Amazon, can help you check moisture levels before you reach for the hose and avoid overwatering newly planted peonies.

So, when should you reduce watering? Do it gradually in autumn, as temperatures drop. Once the ground freezes, stop supplemental watering.

5. Apply Mulch

I like to think of mulch as a snuggy blanket for my plants, but it actually serves a bigger purpose. Mulch keeps the soil warmer, holds in moisture, and keeps down weeds. Autumn plant maintenance almost always includes mulch.

But when it comes to peonies, there are certain mulch rules that you have to keep in mind. First, established plants don’t need mulch. Only use mulch on new or newly transplanted peonies.

Second, don’t cover the buds (aka eyes). Instead of a snuggly blanket, apply a light, loose ring of mulch around each new or transplanted peony. This prevents frost-heaving during the first winter.

Third, pick your mulch type carefully. Don't use any mulch that can trap moisture since it can rot the crown. Instead, use a light layer of straw, shredded leaves, or evergreen boughs. If you don't have your own straw, EZ Straw Seeding Mulch, available from Home Depot, is a convenient option that provides insulation while still allowing air to circulate around the crown. Avoid compost, fresh manure, or sawdust.

6. Plant New Peonies

Autumn is one of the best times of year to plant peonies. Cooler temperatures and still-warm soil give new plants plenty of time to establish roots before winter arrives, setting them up for strong growth the following spring. Whether you're planting a nursery-grown peony or a division from an established plant, getting it into the ground in October gives it the best chance to settle in before dormancy.

Choose a sunny spot with fertile, well-drained soil, and avoid planting the crown too deeply. The buds, or "eyes", should sit no more than 1–2 inches (2.5–5 cm) below the soil surface, as planting too deeply is one of the most common reasons peonies fail to bloom.

If you're planting into heavy clay or poor soil, mixing in a quality planting mix such as Miracle-Gro Garden Soil for Flowers, available from Walmart, can help improve drainage and give new peonies the best possible start.

Water thoroughly after planting, then apply a light ring of mulch around new plants to help protect the roots through their first winter, taking care not to cover the buds.

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