Peonies are popular plants in many parts of the world. They are revered for their spectacular blooms and great fragrance. A common problem that some gardeners face is peonies turning red.
Lack of phosphorus and too much sun exposure are the most common reasons why peonies turn red. Additionally, production of anthocyanin pigments and fungal diseases can also cause red leaves in peony.
Let’s find out why peonies turn red and what you can do about it. We give you the possible causes and what you can do about it.
Why do peony leaves turn red?
Here are some common issues that could be causing the problem and how to fix them.
This is a fairly common fungal disease in older varieties of peony. The new variants are a bit tougher.
It is commonly called peony leaf spot, peony measles, or peony red spot. It starts out as red to purple spots on the top of the leaf with brown spots on the underside. Red streaks can also be seen on the stems.
Once you have this problem, it can be very difficult to deal with. Prevention is always the best measure.
If your plant is infected, remove and discard all infected stems and leaves. Cut the stems at ground level. This should be done in late fall or early spring.
Use a fungicide if new growth appears. Sterilize the surrounding soil and any new growth on the plant. Repeat weekly and watch the growth as it develops to see if you need to spray again.
A buildup of anthocyanins can lead to red peonies. It is a red to violet colored pigment.
When a plant is stressed, this pigment can build up. The cause can be several factors, such as cold temperatures, too little water or disease.
The solution is to keep the plant happy and healthy. Provide plenty of water, but not too much. Check that there are enough nutrients in the soil and add more if necessary.
If it is in a container or jar, bring it indoors or indoors on freezing nights. If you leave it outside, you can use an antifreeze cloth.
Xanthomonas leaf spot
This disease, also known as bacterial blight, is not only identified by the reddening of the leaves, but you may also notice yellow rings around the infected area.
Again, it is unfortunately difficult to treat this bacterial infection once it occurs. If your plant is in pain, cut off and discard all infected parts of the plant.
Make sure the plant has good air circulation by removing surrounding growth that may be crowding it.
Do not water from above and remove all surrounding dirt. Treat with a preventative fungicide if new growth appears.
Nutrient deficiency is a common problem, especially with potted or indoor plants. Too much is a problem, but too little will lead to poor growth and flowering. Low phosphorus levels often cause the leaves to turn red.
Plants need a variety of minerals and nutrients to thrive. The main ones are:
- nitrogen (N)
- phosphorus (P)
- potassium (K)
Most commercial fertilizers give NPK numbers which indicate the ratio of the three nutrients.
While all are essential for various aspects of plant growth and performance, a phosphorus deficiency in peony can cause leaves to turn red and cause other problems.
Sometimes it is not a lack of phosphorus that is the problem, but other factors that prevent the plant from absorbing these and other nutrients. This can be caused by cold soil, an aging plant, or other factors.
Feed the plant with a fertilizer high in phosphorus. Make sure other conditions such as light, water and temperature are favorable. If the plant is getting old, it may be time to replace it.
If the plant is in a pot, the soil may be old and have lost much of its nutritional value. Transplant the plant with fresh, quality potting soil.
A lot of sun
While peonies like lots of sun, this can be a problem. This is especially true for some varieties.
If you think too much sun is causing the problem, you can try gently moving the plant. Another option is to place a taller plant on top to shade the peony from the midday sun.
lack of light
Too little light is another problem that can stress the plant and cause the leaves to turn red. Peonies need 6-8 hours of sun per day.
If the plant is in a pot, especially houseplants, you just need to move it to a position that receives more light.
If it is on the ground, you can prune surrounding plants and foliage to let in more light. If that’s not possible, consider digging up the plant and planting it in a sunnier location.
While overwatering can be a problem, under water can turn peonies red. When the roots dry out, the plant experiences stress, which can affect the pigmentation of the leaves.
A peony usually wilts and drops its buds when thirsty. Dried red leaves are the next step. You need to keep an eye on the plants to make sure they are getting enough water.
This can be done by sticking a finger in the ground. If the top two inches are dry, your peony will need water. Try to avoid the water from above. You can also use a moisture meter to test the soil.
Are you afraid that the peony will turn red?
In general, the causes of peony leaf redness are not life-threatening. They give the plant an unhealthy appearance and are a sign of distress. A cheerful and healthy peony should not have red leaves.
If the problem is left untreated, it can lead to more problems, poor growth and less prolific flowers. It is important to determine the root cause of the problem and take steps to fix it.
Another reason to act is that a stressed plant is more susceptible to further infection or insect attack. A healthy plant is usually able to fight off problems naturally.
If you have a persistent problem with your peonies turning red, the variety may not be right for your area. Many of the new varieties available are stronger and less prone to the problems red leaves can cause.