We all enjoy peonies’ attractive blooms every spring and summer, even though they typically start fading in the middle of summer. These perennials need adequate care in the fall to ensure that you can see them bloom again in the following year.
Below are the steps to care for peonies in the fall:
- Cut your herbaceous peonies to the ground.
- Remove debris and weeds around your peonies.
- Apply fertilizer as needed.
- Apply mulch around the plant’s crown.
- Reduce the frequency of watering.
- Stratify your peony seeds.
- Move peonies after they go into dormancy.
- Divide overgrown peonies for propagation.
The rest of the article will discuss these steps in more detail to help you care for your peonies properly in the fall. Whether you want to ensure they grow in the following year or propagate them in the fall, this article will also cover such topics. Read on to learn more!
1. Cut Your Herbaceous Peonies to the Ground
There are three categories of peonies when it comes to their cutting or pruning needs. Tree peonies only need minimal pruning, such as deadheading spent blooms. However, herbaceous and Itoh peonies (hybrid between herbaceous and tree varieties) must be cut to the ground in the fall.
While individual peony flowers bloom for roughly 10 days, a peony plant’s blooming period typically lasts at least 6 weeks, from late spring to early summer. Some cultivars can even bloom until the middle of summer.
Generally, peonies stop blooming sometime between July and August, and the foliage gradually dries up and dies. However, the end of the blooming period depends on the peony variety, which could be early, mid-season, or late bloomers.
Regardless of the variety, it is best to wait until the foliage fades before pruning your peony plant to allow it to generate enough food and energy for the buds that develop underground.
Removing the leaves too soon will leave you with weak buds that cannot produce flowers next year so it’s important to let the foliage die naturally. Peonies use this period to absorb energy from the above-ground foliage which is stored until the next growth season when it’s needed.
When properly cared for, these buds will develop and sprout when the temperatures rise high enough after winter.
Inspect the leaves before they completely dry up for any sign of damage besides the natural drying process. Peonies are susceptible to bacterial or fungal infections that can survive through winter and cause severe damage to the plants during the growing season.
Cutting your peonies to the ground after the blooming period is a crucial process to carry out every fall to ensure that your plants stay healthy and regrow in the spring. Otherwise, you risk exposing your plants to winter injury that they may not survive until spring.
Once all the leaves have turned brown and died, you must cut the stems and branches down to the ground. It is vital to use sterile garden shears to protect your plant from microbial infection.
Wash and sterilize the tools again before moving on to the next plant. Failure to do so may result in the spread of disease from one plant to another.
It also helps to cut the branches diagonally at a 45° angle to reduce the surface area harmful microbes can invade. As mentioned, peonies are vulnerable to infections, especially with cutting wounds.
Inspect the cut branches and leaves for any unusual signs of decay if you want to use them for mulching or compost. Repurposing infected leaves will only spread the disease. Some gardeners burn the cut leaves and branches to avoid any problems.
2. Remove Debris and Weeds Around Your Peonies
After cutting back your peony plants, it helps to ensure that the area is void of weeds. In the fall, as temperatures drop, gardeners reduce the frequency of watering, so you wouldn’t want weeds to steal what little moisture is available to your peonies.
Below are some things to remember when removing weeds:
Weeds Are Competition
Weeds will compete with the peonies’ roots for moisture and nutrients. Removing the weeds will ensure that your peonies still get sufficient water and essential nutrients to support the developing buds.
Remove the Weeds From the Roots
When necessary, use a hand shovel to make sure you can pull the weeds from the roots. Simply pruning or pinching the shoots and blades aboveground is not enough to remove them.
If the roots stay in the soil, the weeds will regrow quickly.
Avoid Using Weed Killers
It can be risky to expose freshly cut peonies to chemicals too soon. Hand weeding is often enough to clear the area of unwanted growths.
If absolutely necessary, you can use chemical weed killers that are safe for peonies. Avoid using acidic ones because peonies thrive best in neutral to alkaline soils.
Remove All Remaining Debris
In addition to weeding, you must remove any debris left on the ground after cutting back your plants. Leaving some debris close to the remaining peonies will expose the vulnerable plant to risks of microbial infections.
Fall is an excellent opportunity to clean up around your peonies since spent blooms and their debris may still be left lying on the ground. When the branches are gone, it will be easy to keep the area around the crown of the plant clean and tidy.
Cleaning up can also help prepare your soil for fertilization and ensure that the fertilizer won’t be wasted on weeds and plant debris.
3. Apply Fertilizer as Needed
Peonies do not need many nutrients in the fall, but they can benefit from good amounts of phosphorus and potassium to keep the roots and the buds healthy and prepare them for the spring.
Avoid feeding a nitrogen-rich fertilizer to your peonies in the fall. Nitrogen-rich fertilizers are better off applied in the spring when the plant needs to grow foliage to support its development during the growing season. Peonies need to strengthen their roots and buds after the blooming period to produce enough blooms the following year.
You can conduct a soil test to check if the ground has adequate nutrients or to determine which essential minerals are missing. It will help you regulate the type and amount of fertilizer to apply around your plants.
After checking the soil test results, apply the necessary fertilizer formula roughly 12 inches (30 cm) away from the plant’s crown. It helps to use slightly less than the concentration required because too much fertilizer can damage the plant.
Water the soil to work the fertilizer into the ground so the plant can use the nutrients before the ground freezes.
If the soil lacks phosphorus, you can use a bone meal fertilizer. Meanwhile, if the soil has low potassium and/or phosphorous levels, you may want to get a fertilizer mix that supplements the respective nutrients.
Good amounts of magnesium and sulfur, which are essential secondary micronutrients, will help increase the number and quality of blooms.
4. Apply Mulch Around the Plant’s Crown
After the first frost, apply at most 2 inches (5.1 cm) of mulch around the base of the plant but not too close or directly above it. Common mulch materials include straw or tree bark, which may contain some harmful microorganisms that can kill off the buds underground.
That’s why it’s best to keep some distance between mulch on the surface and the buds. An inch or two (2.5-5 cm) below the ground should be fine.
Heavy mulching may also be counterproductive for the buds that need to be close to the surface for better bloom yield in the spring. Peonies are pretty sensitive to depth. Although the plants may grow and produce healthy leaves in spring, the flowers might not bloom if there’s a thick layer of mulch above the ground.
However, when done correctly, mulching can help suppress the growth of weeds by blocking the sunlight and occupying the space the weeds need to sprout. It can also help regulate the soil temperature for the roots and buds and improve moisture retention, considering the reduced watering frequency.
If your area has harsh winter conditions, you may need to apply a thicker layer of mulch around your plant. In this case, you can apply up to 4 inches (10 cm) of mulch.
Remember to remove the mulching materials as the temperatures rise and stay above 60 °F (15.6 °C) in spring.
5. Reduce the Frequency of Watering
Peonies do not need much water in the fall, but they can benefit from sufficient moisture for the developing buds. Hard frost may cause the water in the ground to freeze, making it dangerous for the peonies’ roots. That’s why mulching is essential to ensure that the roots and buds are safe from winter elements.
Apply water only when necessary. Typically, you should apply water after fertilizer application and after laying down the mulch. After which, reduce the watering frequency to once every two to three weeks in the fall.
When the temperatures drop below 50 °F (10 °C), you can stop watering your peonies. The plant will enter dormancy at the middle or end of fall if soil and air temperatures stay below this level.
Only add enough water to keep the soil damp and allow the mulch to do its job until the growing season.
6. Stratify Your Peony Seeds
Although it isn’t necessary in all cases, some gardeners who want to grow new peony plants from seeds need to expose them to regulated temperatures and controlled environment setups. Unpredictable weather patterns and short periods of warmth and cold can make it difficult for peony seeds to germinate.
Consequently, you can stratify the seeds to improve their chances of getting peony seedlings in spring. If you plan to grow peonies from seeds, fall is the best time to stratify them. The process involves steps that guarantee the seeds will germinate in spring.
Some essential things to remember when stratifying seeds include the following:
Some Seeds Require Manual Scarring
Some peony seeds require manual scarring of the outer layer. Dark-colored peony seeds need human intervention to break out of the first stage of their double dormancy.
Seed Behavior Depends on Chemicals
The behavior of peony seeds depends on phytohormonal mechanisms. The chemical abscisic acid promotes dormancy among peony seeds. On the other hand, gibberellic acid encourages them to break out of it.
They’re Sensitive to Light & Temperature
The germination of peony seeds is sensitive to light and temperature. Seeds need the late summer warmth and two successive cold periods in the fall and winter to successfully germinate in spring.
Insufficient duration of cold will compel the seeds to delay germination for another year.
Stratification Isn’t Always Necessary
Seeds can germinate even without stratification under ideal conditions. However, there is no guarantee that they will germinate in spring due to unpredictable weather patterns and other factors, like birds feeding on them.
Non-Germinated Seeds Can Still Sprout
Peony seeds that failed to germinate in spring can still sprout successfully in the following year. However, if they fail to do so in the second year, the odds that they ever would reduce with each passing year.
On average, peony seeds remain viable for three years, with a significant decline in vigor after the third year.
7. Move Peonies After They Go Into Dormancy
Most established peonies do not respond well to transplantation or moving. That’s why if you have plans to move your mature peony plants, the best time to do so is in the fall when they have entered dormancy.
Peonies need ample time to establish their roots before the ground freezes in winter. As such, it is best to move peonies in September. However, plants transplanted in October can still survive as long as you move them properly.
Before pulling out your peony from the ground, dig up the area where you plan to move your plant. It can help reduce the stress your plant has to endure.
It also helps if the new site has the same type of soil with the following qualities:
- Neutral pH (7.0)
- Good drainage
- Rich in humus
Carefully dig around your peony plant with a clean shovel, and dig deep enough to pull out the roots. Remember that the roots of an established peony plant can be massive. You can cut the smaller lateral roots, but it helps to keep most of their bulk.
Transplant the peony immediately into the new site. Ensure that the eyes or buds are only 2 inches (5 cm) below the ground’s surface. Any deeper, and you will compromise the number of blooms in spring.
Water the transplanted peony thoroughly until the soil stops absorbing water. As mentioned, you will need a substrate with good drainage. Add more water after two weeks as needed or when the top 1-2 inches (2.5-5 cm) of soil appears dry.
Peonies thrive best when left undisturbed and can even tolerate a bit of neglect. That’s why it helps to plan their location carefully from the get-go. Move your peonies only when highly necessary, such as when there’s plenty of competition for moisture, nutrients, and sunlight in the area.
8. Divide Overgrown Peonies for Propagation
Another instance where gardeners need to dig up their peonies is when the roots are overgrown. If this happens, the quality of the blooms may not be as good as before. That’s why it is sometimes necessary to divide the peonies.
Ideally, you should divide overgrown peonies only once in five to ten years. You can do it more often if you have limited space in your garden, as overcrowding can become a serious issue for the mother plant.
Follow the same steps when transplanting peonies, but skip the last part. Instead, you will need to wash away the soil to expose the buds or eyes. It will help direct you on how and where to cut.
Cut through the roots using a sterile knife or sharp gardening tool, ensuring that each portion has at least three buds. Plant them into the ground immediately and water them thoroughly.
Apply 2-3 inches (5-7.6 cm) of mulch on the soil’s surface and leave a marker on the ground to help you locate your peony transplants immediately.
Repeat deep-watering once every two weeks until the temperatures drop below 50 °F (10 °C) – after which you will need to stop watering your peonies.
Peonies are perennials that can last a lifetime. However, they might fail to produce their characteristic beautiful flowers some years, depending on whether they can survive the cold in the fall and winter.
The number and quality of a peony plant’s blooms in spring and summer depend on how well gardeners tend to the plant in the previous year’s fall, making adequate care after the blooming season crucial for successful blooms in the following years.
Following the recommendations above can help you provide adequate care for your peonies,keeping them healthy and thriving for years to come.