Why are Peony Leaves Turning Red? (Causes And Solutions)


Peonies are popular plants in many parts of the world. They are revered for their dramatic blooms as well as their awesome fragrance. One common issue that some gardeners face is peony leaves turning red. 

Lack of phosphorous and too much sun exposure are the most common reasons for your peony leaves turning red.  In addition production of anthocyanin pigment and fungal diseases can also result in red leaves on your peony. 

Let’s look at the reason why you might find peony leaves turning red and what to do about it. We will give you the potential causes as well as what to do about them. 

Why Are Peony Leaves Turning Red?

Leaves on Peony Turning red

Here are a few of the common issues that might cause the problem as well as how to deal with them. 

Cladosporium paeoniae

It is a fungal disease that is fairly common in older varieties of Peony. The new variants are slightly more resistant. 

It is commonly known as Peony leaf blotch, peony measles, or peony red spot. It starts with red to purple spots on the upper side of the leaf with brown patches on the underside. Red streaks might also be visible on the stems. 

Solution

Once you have this problem it can be very difficult to treat. Prevention is always the best measure. 

If your plant becomes infected remove and disposes of all infected stems and leaves. Cut the stems right down, to ground level. This should be done in late fall or early spring. 

Use a fungicide as new growth appears. Spay the surrounding soil as well as all new growth on the plant. Repeat weekly and monitor the growth as it develops to see if you need to spray again. 

Anthocyanins Pigment 

An anthocyanin accumulation could lead to red peony leaves. This is a pigment that is red to purple in color. 

When a plant is under stress, this pigment could accumulate. The cause could be several factors such as cold temperatures, too little water, or disease. 

Solution

The solution is to keep the plant happy and healthy. Ensure it has enough water, but not too much. Check that it has sufficient nutrients in the soil and feed if necessary. 

If it is in a container or pot, take it indoors or undercover on frosty evenings. If left outdoors, you could use a frost cloth. 

Xanthomonas Leaf Spot

Otherwise known as Bacterial blight, this disease is identified not only by the reddening of the leaves but you might also notice yellow rings around the infected area. 

Solution

Again, unfortunately, it is difficult to treat this bacterial infection once it has set in. If your plant is suffering, you need to cut back all infected parts of the plant and dispose of them. 

Make sure that the plant has good air circulation by removing surrounding growth that might be crowding it. 

Do not water from above and remove all surrounding debris. Treat with a preventative fungicide as new growth appears. 

Phosphorus Deficiency

Nutrient deficiency is a common problem, especially with potted or indoor plants. Too much is a problem but too little will result in poor growth and blooming. Low phosphorus levels will often result in leaves turning red. 

Plants need a range of minerals and nutrients to prosper. The most important are 

NPK:

  • nitrogen (N)
  • phosphorus (P)
  • potassium (K) 

Most commercial fertilizers will give the NPK numbers showing the ratio of the three nutrients. 

While they are all essential for different aspects of the plant’s growth and performance, a phosphorus deficiency in the peony could cause leaves to turn red as well as cause other issues. 

Sometimes, it might not be a lack of phosphorus that is the problem but other factors that cause the plant to lack the ability to absorb this and other nutrients. This could be caused by cold soil, an aging plant, or other factors.

Solution

Feed the plant with a phosphorus-rich fertilizer. Ensure that the other conditions such as light, water, and temperature are favorable. If the plant is getting old it might be time to replace it. 

If the plant is in a pot the soil could be old and have lost much of its nutrient value. Repot the plant with fresh quality potting soil. 

Too Much Sun

While peonies like a fair amount of sun too much can be a problem. This is especially true with certain varieties. 

Solution

If you believe that too much sun is the cause of the problem you could try to carefully relocate the plant. Another option is to position a larger plant above to protect the peony from the midday sun. 

Lack of Light

Too little light is another problem that could stress the plant and cause the leaves to go red. Peonies need a good 6 to 8 hours of sun per day. 

Solution

If the plant is potted, especially indoor plants, you simply need to move it to a position that gets more light. 

If it is in the ground you can prune back surround plants and foliage to allow more light in. If this is not possible, you will have to consider digging the plant out and planting it somewhere that gets more sun. 

Underwatering

Although overwatering can be an issue, underwatering is a problem that could cause peony leaves to turn red. As the roots dehydrate the plant is under stress and this could affect the leaf pigmentation. 

Solution

A peony will generally wilt and drop buds when it is thirsty. Dry red leaves are the next stage. You need to keep an eye on the plants to ensure they are getting enough water.  

This can be done by inserting a finger into the soil. If the top inch or two is dry, your peony needs water. Try to avoid watering from above. You could also use a moisture meter to test the soil. 

Should You Worry About Peony Turning Red?

Generally, the causes of peony leave turning red are not fatal. They do make the plant look unhealthy and are a sign of distress. A happy and healthy peony should not get red leaves. 

If the problem is left untreated it could lead to further problems, poor growth, and less prolific flowering. It is important to determine the underlying cause of the problem and take steps to correct the issue. 

Another reason to take action is that a plant under stress is more susceptible to other infections or attacks from insects. A healthy plant is normally able to fight the problems off naturally. 

If you have an ongoing problem with your peony leaves turning red, it might be that the variety is not suitable in your area. Many of the new varieties available are hardier and less prone to the problems that could cause red leaves. 

Arifur Rahman

I'm the owner of gardenforindoor.com. After completing my bachelor of science in agriculture, I'm serving as a civil service officer at the Department of Agricultural Extension, Bangladesh. I started Garden For Indoor to make your indoor gardening journey easy and enjoyable.

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