In general, peonies are undemanding plants that are easy to care for. Leaf curl is the one problem that you might find yourself facing. Whilst you shouldn’t be too alarmed by this, you need to treat it as a sign that your Peony needs some help.
Watering is the most common cause of this problem, though there are several other potential issues that we will be looking at in this article.
The main thing to be aware of is that these are robust plants and dealing with leaf curl is not beyond the abilities of even the most novice gardener, if you simply follow the advice below.
Leaf curl is the method by which your peony will let you know that it is unhappy. There are several potential reasons, but watering issues are the most likely cause. This can easily be rectified.
Peony Leaves Curling Due to Underwatering
These plants can take a certain amount of drought and so they will survive the occasional dry period. If that persists for too long, however, the leaves will begin to curl inwards as your plant starts to demonstrate its distress.
That said, they like free draining soil and their shallow root system means they benefit from a shallow watering once or twice a week rather than a deep watering.
Ideally, you want to keep the soil moist but never too wet. To do this, I check my plant every few days by the simple low-tech method of poking my finger into the soil to the depth of about an inch.
If what I feel is cool and damp then all is well. If that top level of soil has become dry then I know that it is time to water.
Lack of Nutrients
One only has to look at a big leafy plant likes this, with its ability to produce abundant blooms to know that it is going to need a certain amount of food. If the moisture level in the soil is correct, your peony’s leaves could be drooping and curling because the plant is hungry.
Strangely enough, I only feed my peonies once a year in the spring. They normally are able to get what they want from the healthy soil.
Each spring I sprinkle a 5-10-5 fertilizer around the drip line of the plant and then give it a slight soaking. If you use a fertilizer that is too high in Nitrogen then your pant will produce too many leaves and not enough flowers.
Unless you happen to live in an area where the soil is depleted, you will be surprised by just how little feeding these plants require.
This is quite a common one with new peonies, though I find that once they have settled in they adapt well. In the US the ideal zone for cultivating is 3 – 8.
To get the best flowering from your peony, they need cooler winters with a few touches of frost. The leaf curl you may be experiencing is likely in the warmer weather where temperatures go really high very suddenly.
Keep your plants moist but not wet during these periods and mulch slightly to retain that moisture.
Do not plant deeply where there is a warm temperature. Use loose and well-draining soil for better results. Plant in a location where it gets shade in the afternoon.
This is a problem that can be a killer. Peonies need well-drained soil and if their feet are constantly wet the roots can rot.
At that point, their capacity to absorb both moisture and nutrients will diminish and their leaves can quickly curl and droop as though they are underwatered and underfed.
You need to diagnose this one quickly and then take action. The finger test will tell you if the soil is waterlogged.
If it is, you need to get the plant out of the soil and allow the root ball to dry out. I lift the plant with a fork (if the soil is waterlogged this is usually quite easy) and stand it on a hard dry surface until all excess water has drained away.
Once dry I gently scrape away any loose soil and examine the roots carefully. It is quite easy to distinguish between healthy root material and that that has started to rot.
Healthy material is firm and white, but rotting roots are soft and flaccid. Cut any rotten material away with a pair of secateurs and then plant your peony in a place where the soil is free draining.
This is a problem that is serious but it is easily avoided by regularly testing the soil to see it is not getting soggy.
To get the best from your peony it is critical that you choose the position where it will be panted with care.
These are plants that can live for many years but having to lift them to treat root rot will put that longevity at risk.
Here’s one that many people don’t think about but the chemicals that most domestic tap water is treated with are not ideal for plants. This is particularly true if your plants are housed in containers.
The salts in chlorine slowly build up around the plant’s root system where they are absorbed by the peony. Over time, they block the pore-like holes in the leaves of the plant and this can cause them to curl.
The easy solution is to get hold of a water butt and trap rainwater. This will not have the harmful chemicals that were designed with humans in mind rather than plants. You may also have access to rain or river water.
Too much sunlight
There are over 3000 different varieties of peony. So, it will come as no surprise that there are some that enjoy less light than others.
Most tree peonies will take harsh sun though they prefer some shade during the course of the day.
Herbaceous peonies tend to err toward preferring slightly less sun but they still need a minimum of six hours of sunlight per day.
In both cases, the leaves will start to curl if your plant gets too much direct sunlight.
This is one plant where I like to consult the nurseryman before making a purchase. If he is worth his salt, he will be able to give exact instructions as to just how much sunlight each of his plants would be happiest with.
Getting the position right in the first place eliminates all the risks involved in lifting a plant and moving it if the lighting is wrong.
Lack of light
If you plant a peony in a position where there is not enough light, the leaves may curl but it is more likely that the plant will just grow away happily and then not reward all your tender care with the flowers that you have been looking for so forward to.
Just as with too much light, the issues created by too little light can be avoided by getting the best advice from your plant supplier.
If that is not possible then look for a spot that offers six hours of direct light per day, and of course, has that all-important, free-draining soil.
Fungal disease is the one disease that you are most likely to encounter or at least the one that is most likely to cause the leaves to curl. Many fungal diseases are also accompanied by powdery mildew or black marks on the leaves.
In this case, prevention is far better than cure. Peonies tend to be trouble-free plants if they are grown in the right conditions.
The two things that will encourage the development of fungal disease are overwatering and not enough light.
Ensure that your plant is draining freely and getting plenty of suns. If those two conditions are met then you have very little chance of fungal issues.
There are several pests that you may encounter, but they need to become quite established in order to cause your peony’s leaves to curl.
- Thrips are tiny brown insects with thin bodies and small wings. They are sap suckers and target new leaf tips and buds.
- Scale insects are another sapsucker that hides beneath a tough outer cuticle. Once established, they never move, but spend the rest of their lives at one pace sucking away at the peony’s sap from beneath their armored fortress.
- Mealybugs look like small cotton balls. They gather in clusters at the base of leaves and in leaf joints where they suck the sap from the plant. They are so small that they sometimes go unnoticed, but in clusters, they are more visible as is the black sticky substance that they secrete.
Both thrips and mealybugs are real wimps and providing you spot them before they become established, they are easily eradicated.
For best results that don’t require harmful chemicals, spray or wipe them away with a vegetable soap or Neem oil.
Because of the hard outer shell that the scale insect hides under, getting rid of them requires a slightly different approach.
I normally just scrape them away using the back of my pocket knife or my fingernail. If they become established in large numbers then it may be necessary to dab them with a horticultural oil that is generally available at most nurseries and plant shops.
Because peonies are such tough plants it is quite easy to assume that they are immune to pests and therefore not to pay them enough attention.
Most of the insects that cause leaves to curl, do so by sucking sap which weakens the plant and deprives it of nutrients.
This only happens if they become established in large numbers. Providing you examine the plants closely, on at least a weekly basis, then this should never happen.
Your peony is far more likely to suffer from excess humidity than it is from low humidity. Excess humidity creates a boon for viral and fungal diseases.
Don’t crowd these plants together among either other peonies or other garden plants. This will ensure that there is plenty of air circulating to prevent humidity build-up.
As we have seen, these plants don’t like to be overwatered. It is important, therefore, to think carefully about who the neighbors are going to be.
If you plant your peony among plants that require high levels of moisture it is likely that there will be some runoff that will make the peony unhappy.
Although I incorporate my peonies into mixed beds, I still separate them slightly from their adjacent plants and choose those plants carefully. I look for neighbors with similar low water needs.
Planting Out and Replanting
There is a common myth that peonies can’t be moved once planted and that they are difficult to get started.
I think that both of these misapprehension stems from the fact that people have misunderstood the plant’s requirements in the first place.
A little knowledge goes a long way here. This plant likes free-draining soil and it does not like to be planted too deeply.
To get the best flowers, purchase an already established plat that is three to four years old so that you don’t have to wait years to see results.
When planting, or moving an established peony, do so in the spring and then don’t overfeed it or over mulch.
Make sure that the top of the roots is no deeper than two or three inches below the soil surface.
- Ensure that the soil is free draining and that the plat will get enough direct sunlight.
- Do not plant too deeply and don’t be scared to buy an established plant so that you see those flowers sooner.
- Avoid the temptation to overwater or water too deeply.
- Check the plant frequently for pests and so that you can monitor the soil moisture levels.
- Don’t go too wild on the plant food.
This is a tough plant but because they are so stunning people tend to mollycoddle them and that is often what leads to health issues.