Why Are My Peonies Dying? 7 Reasons

Peonies are one of the hardiest perennials that you can grow. They require very little maintenance. But, like all plants, there are a few problems associated with growing peonies, and some of these may even cause your peonies to die.

The most common reasons why your peonies might be dying are: 

  • Not enough water
  • Excessive heat
  • Over-fertilizing
  • Leaf Blotch
  • Peony Wilt
  • Phytophthora Blight
  • Overwatering

Let’s look at these issues in more detail so that you know how to fix them and prevent them in the future.

Not Enough Water

To tell if your peony is suffering from not enough water, you need to look at the foliage and at the soil around your plant. When a peony wilts from being under-watered, the plant will wilt, and the leaves will turn brown and feel dry and brittle.

If you see this happening, check the soil around the plant. Does it appear to be really dry? You can get an idea of the dryness of your soil just by pushing your finger into the top layer. Or, you can use a moisture meter that you should be able to buy from your local garden center.

Either way, if your plants are wilting and the soil is dry, your peonies need a good drink. You can water them with a hose, or a watering can but make sure you give them deep watering. It’s also important to remember to direct the water at the roots of the plant and avoid wetting the foliage or the flowers.

Watering your plants from above makes them more susceptible to fungus diseases.

Excessive Heat

Although peonies do grow and flower much better when they’re exposed to plenty of sunlight, prolonged temperatures above 90 degrees Fahrenheit (32 degrees Celsius) can cause the leaves to burn and turn brown.

If your area is experiencing some hot temperatures in summer, you might like to supply your peonies with some afternoon shade. For this, you can set up a structure with some shade net or place some taller growing plants in pots near your peonies.

It’s also important that your plants do not dry out when the weather is scorching. Keeping them well-hydrated will protect them from the searing heat of the summer sun.

Over Fertilizing

Over-fertilizing your peonies can burn the leaves of your plants, causing them to die off. This is especially true if the fertilizer is high in nitrogen. Be careful with peonies that are planted near lawn areas, as the lawn fertilizer that you’re using may seep into the soil where your peonies are growing.

Peonies don’t require a lot of fertilizer, but they do benefit from a little in early spring. Make sure that the fertilizer that you select is low in nitrogen and high in potassium, as this will stimulate plenty of flower growth.

Leaf Blotch

Leaf blotch is a fungal disease caused by the Cladosporium paeoniae fungus. To identify this disease, you have to take a close look at the leaves of your plant. If the leaves of your plant have small red to purple spots very close to the veins, then your peonies may be suffering from leaf blotch.

If you don’t treat this fungus, the spots will grow and also spread to the plant’s stems. Eventually, all the leaves will turn from purple to reddish-brown.

As with most fungal diseases, the best cure is prevention. Make sure that you only water your peonies at the soil level and try to keep the leaves as dry as possible. That’s because most fungus diseases spread readily through the water.

It’s also important to remove any fungus-affected foliage from both on and around the plant. Put this in a sealed plastic bag and throw it in the garbage bin. Never put this into the compost because the temperature might not get hot enough to kill the fungal spores.

As a preventative measure, you can apply a fungicide to the leaves and stems of your plants in spring. Remember to also spray the surrounding soil as the fungal spores might be hiding there.

Peony Wilt

Peony wilt, also known as botrytis blight, is another fungal disease caused by the Botrytis paeoniae fungus. It causes the leaves and stems of your peonies to turn brown and wilt. The fungus actually attacks the tissues of the plant, and this causes the plant itself to wilt. You may also notice a dark grey fuzzy mold on the plant where the fungus is present.

Additionally, if your plant is suffering from peony wilt, the flower buds will turn brown and will not open.

The best way to treat this fungal disease is to remove the affected foliage and put it in the trash or burn it. Be sure to also remove any weeds or other garden debris from around the plants where the fungal spores may be hiding. Remember to disinfect your secateurs or other pruning tools after you do this.

Phytophthora Blight

Phytophthora blight is yet another fungal disease that may attack your peonies. It is caused by the Phytophthora cactorum fungus. If the stems and leaves of your peony are turning dark brown to black, it may be suffering from this fungal disease.

One of the best ways to control this disease is to prevent bringing diseased plants into your garden in the first place. It’s also vital that you plant your peonies in well-draining soil and to ensure that there’s plenty of air circulation between your plants.

More often than not, if Phytophthora blight is present in your peonies, you’ll have to dig up the plant and destroy it as there is no adequate control for this fungal disease. If this is the case, avoid planting another peony in the same spot as the fungal spores may live in the soil for some time.

Ultimately, the best way to prevent any fungus diseases from developing is to cut back all the foliage in late fall and dispose of it. Also, remember to remove any other debris from around the base of the plants. This means that any fungal spores will be removed, and your plants will be safe for next season’s growth.

Over Watering

Peonies do not tolerate wet feet and need well-drained soil to thrive and grow. However, the symptoms of overwatering can be similar to those of underwatering. In both cases, the plants will wilt, and the leaves will turn brown.

So, how do you tell the difference? It’s quite simple. If your plant has been underwatered, the leaves will be dry and crisp. However, if your plant is suffering from too much water, the leaves will be brown and mushy.

Overwatering may also cause the underground tubers to rot, and this will certainly be the end of your plant. Therefore, if your plant is growing without good drainage, it may be necessary to move it to a better spot. Bear in mind, though, that peonies don’t like being moved and will usually fail to flower the following year or two.

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