Mandevilla Leaves Curling (5 Research-Based Causes & Solutions)
This article explores all the causes of mandevilla leaves curling and guides you through the solutions to save your plant, all based on scientifically backed research papers.
Mandevilla is a group of magnificent flowering vines that adds colors to fences, borders, and walls. Even though they are celebrated for their flowers, unhealthy leaves soar to the eyes.
Mandevilla leaves curling is one of the very commonly seen problems reported by gardeners.
Bacterial & fungi diseases and overwatering are the two main causes of mandevilla leaves curling. If neither of these two problems is present, then other causes like improper lighting, lack of nutrients, excessive salt buildup, temperature stress, or low humidity are the ones to be blamed.
Now you know what the causes of mandevilla leave curling are, let us take a deeper look at how they are linked.
1. Diseases
The number one reason for mandevilla leaves curling is diseases caused by bacteria, fungi, and other pests and insects.
According to numerous scientific studies (check sources section), mandevilla plants are known to be a vulnerable target for many diseases. The bacteria, viruses, and fungi causing the diseases are Ralstonia Solanacearum, Phytophthora, Catharanthus Mosaic Virus, Colletotrichum Fructicola, and many more.
If your mandevilla plant is suffering from any of the diseases caused by the above agents, it will have many other signs than just curly leaves. Check for brown leaf spots, stem rot, etc before coming to a conclusion.
Fix Diseases
If the infection is starting stage (only when very few leaves are curly), then you can use essential oil or neem oil spray. However, if the infection is severe, you must use chemical-based treatments.
2. Improper watering
If your plant is not affected by any diseases mentioned above, then the following commonly seen reason for mandevilla leaves curling is improper watering.
Improper watering can be either overwatering or underwatering. Both of these cause mandevilla plants to curl leaves, but for different reasons.
When you overwater your mandevilla vine, the soil becomes cloggy and fills up all the air pockets preventing roots from proper aeration. Also, mandevilla roots standing in water for a long time have a high risk of root rot which is a much more serious risk.
On the contrary, underwatering makes the plant dehydrated. When you submerge your mandevilla plant, they lose a biological component called turgor, which is responsible for rigidifying the living plant tissue, according to a study that was published in Nature.com. When this turgor is lost, leaves start to curl and preserve existing water until it gets water next time.
Fix Improper Watering
Creating a proper watering schedule after considering the climatic conditions is the ideal way to solve overwatering and underwatering problems. The general rule of thumb is to water your mandevilla plant once a day if they are in full sun. However, in the long run, you can experiment with the frequency depending on how the plant behaves.
3. Fertilizer Issues
Fertilizer issues can be either lack of nutrients or overfeeding which both results in distress for your mandevilla plants.
When your mandevilla plant does not get enough nutrients from the soil mixture, it cannot produce the required energy to perform day-to-day plant functions which will make its leaves curl and droop.
Multiple greenhouse studies mentioned in the resources section suggest that mandevilla plants require iron, chlorine, boron, manganese, zinc, copper, molybdenum, and nickel as important nutrients. Therefore, you must ensure that your mandevilla plant receives all essential nutrients, either in the form of fertilizer.
Fix Lack Of Nutrients
Experts recommend adding slow-release or controlled-release fertilizer twice a year, preferably before spring and in late summer to improve the overall growth of the plant. Additionally, a bloom booster fertilizer once a month during their blooming season is recommended to make the plant produce healthy flowers.
On the contrary, too much fertilizer will increase the salt formations in the soil. These salts will get into the air pockets in the soil mixture and decrease the soil’s aeration and as a result, the plant functions are affected which leads to the curling of leaves.
Fix Overfeeding
If overfeeding is the cause of mandevilla leaves curling, then replant your plant in fresh soil without fertilizer. Also, water deeply so that the plant can recover from fertilizer stress much faster.
4. Poor light
Mandevilla plants prefer full sun, which means direct sunlight for 6 hours a day. However, most gardeners keep these flowering vines in their outdoor gardens where it is very hard to control the amount of light falling on the plant.
It is a known fact that light is necessary for any plant, not just mandevilla. Without proper light plants can’t do photosynthesis and other plant functions needed for their growth and survival.
Mandevilla plants are capable of surviving 6 to 7 hours of direct sunlight a day. But when it gets more than that, the leaves start to lose moisture and get dehydrated which in turn appear curly or droopy.
On the contrary, if the plant is not getting atleast 4 to 6 hours of direct sunlight, it causes photosynthesis and other plant functions to slow down. Slower photosynthesis makes the plant deprived of enough energy which results in leaves curling and similar ailments.
If you are not sure whether your mandevilla is getting too much or too little light, it’s very easy to find out. Your plant is not receiving enough light if the curl is in the direction of the sun. On contrary, the plant is receiving too much light if, the leaves are curling away from the sunlight.
Fix Poor Light
In case of too much light, try to move the plant to a better spot where it gets only 6 to 7 hours of direct sunlight. If that is not possible, use a diffuser to reduce the intensity of light falling on the leaves. When your plant is not getting enough light, the only option is to put them in the brightest spot in your garden.
5. Heat & humidity stress
In most cases, heat stress is directly related to the amount of light your mandevilla plant gets. The more direct sunlight a spot gets, the hotter it will be for plants and vice versa.
Under extreme heat, the leaves lose water much faster than in normal conditions. And, the roots will not be able to supply sufficient water to the leaves at the same rate at which they are losing. As a result, the leaves appear curly and droopy.
To help your mandevilla recover from heat stress, here are a couple of things you can try.
- Deeply water the plant in the morning.
- Place some temporary shading like shade cloth during the hottest time of the day.
- If possible, move the plant to a shady spot for a few hours a day.
Mandevilla thrives in humid environments. Just like heat stress, humidity stress can also take a toll on the appearance of your mandevilla plant.
These plants come from tropical regions like Mexico, the southern US, and West Indies, where the average humidity is very high all year. When the humidity is less, the air becomes very dry, and the rate of transpiration increases which leads to leaves curling.
Fix Heat & Humidity Stress
Controlling outdoor humidity is not a straightforward task. You can place some trays filled with water around your mandevilla plant so that the water gets evaporated and the air around your plant will have higher moisture content.
Conclusion
Now that you know what is causing your mandevilla leaves to curl, the next step is to take action proactively, fix the root cause, and save your plant from further damage.
If the cause is either disease or overwatering, immediate action is needed. Even a small delay in treatment can make the issue more serious and fatal for your plant.
Even though these plants are considered to be quite low maintenance, they need the right soil, water, light, and temperature to thrive.
Sources
To back up the information we provide in our articles, the Plantials team only uses high-quality sources published in peer-reviewed university or scientific research journals.
- First Report Of Bacterial Wilt In Mandevilla (= Dipladenia) Splendens ‘red Riding Hood’ In The United States Caused By Ralstonia Solanacearum Biovar 3, APS Journals.
- Root And Basal Stem Rot Of Mandevillas Caused By Phytophthora Spp. In Eastern Sicily, APS Journals.
- First Report Of Catharanthus Mosaic Virus In Mandevilla In The United States, APS Journals.
- First Report Of Anthracnose Of Mandevilla × Amabilis Caused By Colletotrichum Fructicola In Guangxi, Southern China, APS Journals.
- Heat Stress Symptoms On Flowering Plants, University Of Maryland Extension.
- Pests In The Urban Landscape, Uc Statewide Integrated Pest Management Program.
- Southern Wilt Of Mandevilla, Michigan State University Extension.
