When and How to Cut Back Peonies

Growing peonies is a joy. For the cut flower gardener, these are some of the most spectacular blooms for floral arrangements. They are large, soft, and have a delicate but wonderful fragrance. Pair that with their attractive foliage, and it’s hard to imagine why any gardener wouldn’t grow these exquisite flowering perennials.

An important aspect of growing these flowers is when and how you cut them back. Pruning and tending to them is not something you do all at one time, so that’s the first thing we need to address. When growing peonies, there will be pruning to do in the spring, summer, and fall. 

Cutting back in the fall is vital to the health and longevity of your plants. But, before we talk about cutting them back at the end of the season, let’s address the lesser pruning in spring and summer. These are important for their own reasons. 

Spring Pruning

The pruning your peonies need in the spring depends on their age. In their first year, don’t allow them to bloom at all. I can’t believe I’m saying this, because I, too, am an impatient gardener. But it’s for the best, I promise. 

Removing all the buds in the first year does something that you will be grateful for in the future. It allows the plant to focus energy on developing strong roots, which make a strong plant. Producing those large flowers requires a lot of energy from a small peony. Cut the buds off in the first year, and you will have bigger blooms for the remainder of the plant’s life. 

After the first year, all you need to do in the spring is deadhead your spent blooms. Wait until the petals fall. Follow the stem down to the first set of leaves below the flower and cut just above the leaves. This will keep your plant looking neat. It also helps to conserve energy which will be applied to healthy foliage and root growth. Removing decaying matter will also help to prevent fungal issues. 

Summer Pruning

In summer, the purpose of pruning shifts from helping preserve energy to maintaining a healthy plant. Because of their large, dense foliage, peonies are susceptible to fungal diseases. Moisture can get trapped in there, and then you end up with things like powdery mildew or botrytis. 

The objective in summer is to maintain airflow through the center of your plants. Inspect for any diseased branches, particularly in the interior. Remove any diseased or damaged branches and if you live in a humid climate, it’s a good idea to thin out the interior.

Summer is also a good time to shape your plants. The purpose of this is sheerly aesthetic, and that is completely ok. You can trim back to a node or set of leaves to shape the top and sides.. You can also cut branches back farther to cause more branching and a fuller plant. 

Cutting Back in the Fall

There is one important factor to consider in this equation, and that is the type of peonies you have. There are two types, and they have different growth habits, so they need different treatment in the fall. If your peonies are the herbaceous type, you want to trim them back to the ground in the fall. If you are growing tree peonies, they need different treatment. For our purposes, we will discuss the herbaceous types first and then get to the tree peonies, which are actually shrubs. 

Fall pruning serves an important purpose in the life and health of your herbaceous peonies. Removing the dead foliage helps to prevent diseases, control insect infestation, and maintain a nice shape for your plants. They will grow back stronger in the spring, and leave behind any issues they may be facing in the fall. 

Step 1: Choose the Right Time

Peonies have dazzling fall foliage. As the weather changes, the leaves will change to a stunning bronze, so you don’t want to cut them back too early. You want to enjoy this aspect of your plants. The ideal time to do your major cutting is after the first frost. Once the foliage turns brown, this is the time to do your cutting.

Peony foliage is not frost resistant, but their roots are. After your first freeze, you will notice the foliage begin to turn yellow and then brown as it dies off. Resist the urge to cut back before this time. The leaves and stems still hold nutrients. Allowing them to remain until they are killed by frost gives the plant time to transfer those nutrients into the roots, where the plant will store them for spring. 

Step 2: Use the Right Tools

Pruning shears are ideal for trimming back peony stems and foliage. Hand shears are easy to use and will do the job perfectly. The stems are woody near the bottom but not especially thick. More important than the size of the shears you use is that they are clean and sharp. Clean, sharp shears make clean cuts. Clean cuts help to prevent disease. 

You should always clean your tools between plants because you risk carrying diseases or pests from one to the other.

Step 3: Cut Back to the Ground

Use your shears to cut the stems back to about one inch above the ground. You want to cut them as low as possible without damaging the crown of the plant. The crown in the area between the roots and the stems. This is where the plant produces new eyes, which will turn into new stems in the spring.

Step 4: Avoid Damaging the Crown

Peonies grow from tubers, which are fleshy clumps of root. Think of a ginger root system or dahlias. The roots are similar in those plants. These tubers grow eyes, which are the buds that will become new stems in the spring. It is important to avoid damaging this part of the plant. Cutting off the budding eyes will prevent the plant from growing new stems in the spring and leave you with unattractive and sparse regrowth. 

You can protect the crown by cutting back only the stems, and not too far. This is why we say to leave about an inch of stem above the ground. This will remove any portions that could be holding onto diseases or harboring pests. 

Step 5: Mulch

Peonies are very cold-hardy. Their roots can withstand temperatures as low as -40° over the winter. Given this fact, it is unlikely that your roots will die without mulch. Even so, mulching over your roots can help insulate the ground and lead to earlier growth. Warm soil means faster growth in the spring. 

Mulching can also protect against soil erosion. For young plants, I would advise using mulch over the winter. Mature plants have established root systems that probably won’t need it. Spread an inch or two of mulch over the tops of the plants loosely, but avoid covering the stems. 

Step 6: Spring Prep

In the spring, clear away mulch and other debris like leaves that have fallen. The objective is to provide your peony with the light it needs to begin producing new growth.

Apply fertilizer at this time, as well. Use a low-nitrogen, slow-release fertilizer. Apply the fertilizer around the drip line, which is about six to 18 inches from the roots, depending on the size of the peony. 

Tree Peony Pruning

Tree peonies have different pruning needs in the fall. In spring and summer, you can follow the same guidelines that you have for your herbaceous plants. Deadhead the spent blooms, remove any dead or damaged branches, and shape your plant as you prefer. Thinning out the interior is another step that you can take with these larger shrubs. It will help to prevent fungal diseases. 

In the fall, these will require a different treatment. They are woody plants that will come back to life in the spring and don’t need to be cut to the ground. Their old branches will produce new foliage and flowers. When trimming these, it’s more a question of plant health and encouraging more attractive growth. Wait until the foliage has turned brown before pruning. 

Step 1: Remove Dead Weight

Before you begin, take stock of your shrub and identify the general health of the plant. Before concerning yourself with shape, remove all dead and diseased branches. Dead wood includes any branch that has no growth on it. Cut as far down as you need to, to remove dead weight. 

Step 2: Prune Budding Branches

For branches that are not entirely dead, you don’t have to remove the entire branch. Move down the branch from the top and locate the first live bud. Directly above the bud is where you will make your cut. 

Make your cut diagonally, angled down and away from the bud. Cutting in this fashion will keep water draining away from the bud. It will heal faster this way. Another objective to make this cut is to encourage branching and outward growth. 

Step 3: Shape Your Shrub

Finally, trim your shrub for shape and overall health. If you have a very vigorous plant, feel free to thin out some of the minor branches in the interior. This will create airflow in the interior, helping to protect your shrub from fungal diseases. 

If your plant is growing large for its space, you can reduce the spread by cutting one or two of the main stems back to the ground. Once you have completed this, cut the entire bush back by about one-third. This will encourage branching and help the plant to produce more of those wonderful flowers.