Dahlia leaves curling is usually a sign that the plant is stressed out, it is not always a serious issue, and you will definitely see your Dahlia leaves curling from time to time. Dahlia leaves curling upwards or downwards are symptoms of different issues. The good news is that in most cases if their leaves are curling the issue is not fatal, most likely just a reaction to getting too little or too much water.
Dahlia leaves can curl for various reasons, including soil dryness, extreme temperature fluctuations, fungal infections affecting the roots and stem, and physical damage in high-traffic areas. Curling occurs as a result of water loss or dehydration-related stress, causing the plant cells to shrink and die.
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Dahlia plants tend to have relatively large leaves, and if the plant has any problems you will see its leaves reacting, usually by curling or wilting. For the most part, curled leaves are normal behavior, although if the leaves also start to turn brown or yellow, then this is a clear sign that the plant has some serious issues. If your Dahlia leaves curl up or down from time to time but seems to be healthy, then don’t worry about it.
Usually, Dahlia leaves will curl due to water issues, too much or too little, and as soon as you address the problem the leaves should go back to their standard shape and form. If the Dahlia leaves are turning brown then you should check out my recent article Dahlia Leaves Turning Brown ( Top 8 Reasons ).
Dahlia Leaves Curling
When dahlia leaves start curling, it can indicate several underlying problems that may be affecting the plant’s health. One common cause of leaf curling is water stress, either from overwatering or underwatering. Overwatering can lead to root rot, causing the plant to curl its leaves as a response to the lack of oxygen in the soil. Underwatering, on the other hand, can cause the leaves to curl and wilt in an attempt to conserve water.
Other possible causes of leaf curling include pest infestations, such as aphids or spider mites, which can cause damage to the leaves and disrupt normal growth. Additionally, environmental factors like excessive heat or direct sunlight can also lead to leaf curling.
Not Enough Water
The main reason why Dahlia leaves curl is due to not having enough water, usually, the leaves will start to look wilted and curl down. The good news is that they will bounce back in a couple of hours after being watered. If the plant doesn’t get water, the curled leaves will start to look like a flag on a windless day, after which the leaves will turn brown, dry out, and eventually fall off. Make sure to place one of your fingers into the soil, and if the top inch is dry then it is most likely that the Dahlia leaves are curling because they are thirsty.
Too Much Water
Overwatering Dahlias is the most common reason why they tend to die, too much water can not only curl their leaves but also create serious issues like tuber or root rot. If you know that your Dahlias didn’t get too much water, then the issue might be with the actual soil. Soil that doesn’t drain well tends to cause a lot of problems for Dahlias, especially clay soil. Make sure to check if the top inch layer of the soil is dry, and only water the Dahlias if it is.
If you have clay soil, you can either amend the soil or simply plant the Dahlias in pots. Dahlia plants can survive for a while in a poorly draining soil, but sooner or later their leaves will start to curl, and if they do not bounce back in a matter of days then they might suffer from tuber or even stem rot. If your Dahlia buds are not opening then check out my recent article Dahlia Buds Not Opening ( Top 5 Reasons ).
High Temperatures
Dahlias are full sun loving plants, but they can suffer from too much sunlight. On hot summer days, it is not uncommon to see the Dahlia leaves curl down, usually, this problem can be easily addressed by watering the plant. However, if the leaves are curling and there are small black spots on them then the Dahlia might be sunburned. Dahlia plants tend to lose a lot of water during the day, mostly through their leaves, this is how they protect themselves from high temperatures.
Once most of the water from the plant has been evaporated the leaves will start to curl or wilt, and given enough time without water, the plant can simply dry out entirely. My personal recommendation is to water your Dahlias in the evening and early morning as well if you see their leaves curling due to heat. If you want to know the reasons why Dahlias do not flower then check out my recent article Dahlias Not Flowering ( Top 7 Reasons ).
Not Enough Direct Sunlight
Dahlia plants need full sun in order to grow healthy, although they can grow in partial shade as well, but how well they grow will be highly situational. If the Dahlia plants do not get enough sun then their stems will start to stretch, which will weaken the entire plant. In addition to this, its leaves will also start to curl down, although if there are a couple of leaves that get plenty of direct sunlight then the Dahlia plant might end up with a couple of normal leaves and some that are curled down.
This issue tends to be more problematic if you grow Dahlias indoors, although cutting down the curled leaves and repositioning the pot next to a full sun window usually fixes the problem.
Root And Tuber Rot
The worst thing that can happen to any Dahlia plant is rot, usually when a tuber starts to rot it can not be saved. The first sign that the tubers or the roots are rotting is that the Dahlia leaves will start to curl down, and if the plant doesn’t bounce back in a couple of days, but only gets worse then I have some bad news for you. In this case, the leaves will stay curled down and change color relatively fast, to yellow, or brown and they will eventually fall off.
If the Dahlia plant is suffering from root rot, then it can still be saved, simply cut off the roots and replant the tuber. On the other hand, if the tubers are starting to rot then you have to cut off the soft and mushy tubers, and replant the healthy ones as fast as possible, just make sure to also change the potting mix.
Not Enough Nutrients
Dahlia leaves will start to curl if there are not enough nutrients in the soil. In addition to curling, the leaves will also change color, at first, they will be pale green and then slowly turn yellow. If you are growing your Dahlias directly in the garden then it is less likely that your Dahlias are suffering from a lack of nutrients. On the other hand, if you are growing your Dahlias in pots then sooner or later the potting mix will run out of nutrients.
If you are growing Dahlias in pots then make sure to use fresh potting mix or compost every year. Dahlias need a lot of nutrients for growing their beautiful flowers, to growing new tubers as well, which means that they tend to be hungry plants.
Pests
Dahlia plants have their fair share of pests, although most of them will not cause the leaves to curl. Aphids, mealybugs, scale insects, and thrips on the other hand can make the Dahlia leaves curl as they are feeding on the sap of the plant. The leaves that are curling due to pests will be all over the place, the same leaves can curl both up and down and generally look contorted. In this case, you should wash off the pest from the plant every day, either with water or with a light water and soap mix.
Diseases
Dahlia plants can suffer from different diseases, the most common ones are Necrotic Spot Virus and Verticillium Wilt. The Necrotic Spot Virus can cause the Dahlia leaves to curl, although their tell-tale sign is the discoloration of the leaves, turning yellow, brown, and in some cases even black. Verticillium Wilt on the other hand is a fungal disease, which will cause the leaves to curl up, then change color to yellow, then brown, and red.
Both of these diseases need high humidity in order to thrive, and oftentimes when a Dahlia plant is suffering from either of these they are very likely to have tuber or root rot as well. In this case, you should cut back on watering the Dahlias too often, and a good fungicide will also help.
Key Takeaways
- Dahlia leaves usually curl if they get too much or too little water, although if the issue is addressed then they should bounce back in a couple of days. High temperatures will also cause the leaves to curl, in this case, you should water your Dahlias twice a day, early morning and in the evening. Tuber rot and different diseases can also make the leaves curl, and usually, they are caused by too much water. Pests that suck the sap from the Dahlia leaves will curl and contort the leaves.
- If the Dahlia plant has curled leaves it usually means that they need to be watered ASAP.
- If the Dahlia leaves are curled and also change color then this could be an indication of disease.