Why My Dahlia Leaves Turning Brown (Known Reasons & Best Cures)

Dahlias are sensitive plants. They can easily get affected by pests and diseases. As a result, the leaves become brown or black. A healthy Dahlia plant has green or dark green leaves. But, if there is any stress or other uneasy conditions, its leaves can become brown.

If this dahlia leaves turning brown issue is not treated properly, then the plant may die.

Overwatering is the main cause of brown dahlia leaves. The tubers and the stem of Dahlia plants can rot for excess watering. Necrotic Spot Virus and Verticillium Wilt are also found behind the brown dahlia leaves.

If the plant is overexposed to the sun, then the plants can become brown, for being sunburned. In the presence of it, the leaves can become crumbly. At first, the leaves become brown, and then gradually fall off.

Dahlia Leaves Turning Brown 
Dahlia Leaves Turning Brown 

If the plant is affected by fungi, its leaves can also become brown. To cure such conditions, you need to use a good fungicide. If the plant doesn’t get its preferred growing atmosphere, its leaves can also become brown.

Don’t worry too much if there are one or two brown leaves on your Dahlia plant. But if there are a lot of brown leaves, you need to take action, otherwise, the plant will gradually die off. It is hard to bloom a flower for such a dahlia plant with brown leaves.

So you need to identify the real reason behind these brown leaves; there may be one or multiple reasons.

Dahlia Leaves Turning Brown: Reason and Solution

Overwatering, inadequate sunlight, poor soil, underwatering, fungal diseases, and pests, are the most common reasons for dahlia leaves turning brown. But, with proper care and maintenance, you can overcome this problem.

But, for it, you need to identify the real reason. Here we will discuss the most common reasons behind this problem and their solutions.


An improper watering process is one of the common reasons for which the Dahlia leaves can become brown. To survive, Dahlia plants need proper and consistent watering. The vascular systems of this plant get easily clogged by muddy soil. Tuberous roots are prone to waterlogging.

These can easily be cured if you stop overwatering. On the other hand, when you don’t give proper water to the plant, its leaves become crunchy and dry. Drought is also a major threat to tuberous roots. And the brown leaves are the very first sign of overwatering or underwatering.

Overwatering/Underwatering Dahlia
Overwatering/Underwatering Dahlia

If you want to keep your dahlia plant healthy, proper watering must be done. You need to water the plant whenever the 1st inch of soil is dry. Don’t let the soil completely dry off. Generally, one or two times a week will be enough, but you must observe the soil’s condition.

If your dahlias become wilt and limp, you put more than the required water into the plant. Overwatering may cause mushy and soft stems. The leaves can become yellow or brown.

If you observe that the edges of the flowers are becoming dry or brownish, it is also an indication of overwatering. You need to water the dahlias one or two times a week.

But if the atmosphere is hot or dry, you must water the plant daily. However, you must ensure that the soil of the plant is moist. But you should not make it soggy.

How to Cure Overwatered/Underwatered Dahlia?

Please follow these watering tips if you want to keep your dahlias healthy.

  • In the spring seasons don’t water these plants more than once a week.
  • Don’t forget to water these plants twice a week in the summer.
  • You don’t need to water the plant in the rainy seasons, as the rainwater will be more than enough.
  • Never leave the soil completely soaked up.

Inappropriate Amount of Sunlight

Like other plants, dahlia also needs proper sunlight to grow. If there is insufficient sunlight, the plant’s growth can get affected and not grow properly. As a result, the leaves of the plant start to become yellow and gradually transform to brown; ultimately, the leaves fall off.

If you keep the dahlia plant in a shaded area, you can see that the plant will die within some days. Brown leaves are one of its indications.

Inappropriate Amount of Sunlight
Inappropriate Amount of Sunlight

If the plant is overexposed to the sun, it is also very dangerous to its health and growth. Its leaves can also become brown for this reason. If you live in a hot region, don’t leave dahlia plants under the Sun for a long time. To plant the dahlia plant, You can consider the south or west-facing, sheltered space of your garden, where sunlight comes most.

What is The Solution?

  • To deal with this problem, you can consider the below-mentioned ways.
  • Plant the plant in an area where sunlight is available for at least 6 hours.
  • If your living place is too hot, or dry, you need to place the plant in a partially shaded area. In such conditions, direct sunlight for a long time can make the leaves yellowish or brownish.

Poor Soil and Nutrients

To survive in autumn and summer, dahlia plants need various nutrients, and soil is the main medium through which they can gain these nutrients. So, dahlias need very high-quality soil that has various types of nutrients. For healthy growth, dahlia plants need 17 types of important ingredients.

Besides, many nutrients, nitrogen, potassium, and phosphorus are the most crucial ingredients that play a crucial role in plant growth. And it consumes these macronutrients in large quantities. If these nutrients are deficient, then leaves start to become brown. 

The soil must have a proper drainage system and be properly loosened. Thick soils are not recommended to plant dahlias. To lose the soil, you can mix sand, or you can consider peat. To make the soil productive, you need to add fertilizer to it. You need to consider some low-nitrogen fertilizers.

Poor Soil
Poor Soil

You can go with such options that are rich in phosphorus and potassium. You can use banana peels. It contains low nitrogen but a lot of potassium and phosphorus. You can consider a bone meal, or chicken manure but don’t apply too much, because excess application can burn the roots.

You can also use eggshells, but don’t put in a lot. While planting a dahlia plant you don’t need to apply fertilizer. After one month from planting, you can fertilize the soil. After that give a break of 3 to 4 weeks, then apply again. And continue this process during the entire season. 

What is The Solution?

Check the pH of the soil before putting water on the plant. Try to keep the pH, somewhere between 5.8 to 6.2. Plant dahlia plants in such a soil that has high nutrient consistency. It is good to use store-bought compost.

Try to add organic materials, such as banana peels, egg shells, bone meal, and chicken manure from time to time. Put a special eye on the drainage system of the soil. 

Dahlia Diseases

Dahlia plants easily get affected by Verticillium Wilt and Necrotic Spot virus. If your plant is affected by Necrotic Spot Virus, its leaves first become yellow, then it turns brown, followed by black, and ultimately these fall off. This virus consumes the sap of the plant.  

Dahlia Diseases
Dahlia Diseases

Your dahlia plant can also get affected by Verticillium Wilt. This is a fungal disease. If your plant is affected, it will start to curl, and its leaves will start to be yellow or brown. In some cases, it turns red. This fungus affects the roots of the plants first, then it starts to degrade. This fungus is mostly found in the moistest soils. So keep checking if the drainage system is working properly or not. 

How to Cure Dahlia Diseases?   

Once your plant is affected by the Necrotic Spot virus, it is almost impossible to save it. To control Verticillium Wilt you can get help from some fungicides. But it is good not to make them a shelter on your plant.


Insects, such as Thrips, Potato Leafhoppers, etc can attack dahlia plants. Usually, they are found on the leaves of plants. These insects start to consume the nutrients from the plant. As a result, the plant feels weak and leaves become yellow and brown. 

Insects on Dahlia
Insects on Dahlia

How to Get Rid of Insects? 

Some insects make a permanent mark on the leaves. This proves their existence. If you found any, immediately trim the leaves. To treat these pests or insects you can spray neem oil on the plant at night. 

Why Frost Damage May Cause Dahlia Leaves to Go Brown?

Frost is another enemy of Dahlia. If you leave the plant for 2 days in frost, then the plant will not die. But it can be severely damaged. Its leaves will become brown and ultimately its productivity will get damaged. Due to low temperatures, its leaves will become brown and gradually fall off.

What is The Solution?

Keep the plant in a comparatively warmer place. If not possible, try to build a greenhouse. Keep the plant in a safe and shaded area on stormy days.

How to Care for Potted Dahlia?

Keep these points in mind if you want to grow a healthy dahlia plant in a pot.You need to follow the proper watering process, check the pH of the soil, from time to time, apply fertilizer on in a month,

keep a special eye on the proper drainage system, and always observe the leaves of the plant very carefully for pests and insects and offer a pleasing atmosphere to the plant. Don’t feel stressed. If its leaves are changing color, then take immediate action.

How to Care for Grounded Dahlia?

If you want to grow a healthy dahlia plant in your garden, keep these points in mind. You need to choose the correct place for the garden.

How to Care for Grounded Dahlia
How to Care for Grounded Dahlia?

You need to find such a place where sunlight comes for at least 6-8 hours, check the soil quality before planting, apply the fertilizer and organic composites from time to time, and make sure there is a proper draining system, pH level of the soil within the limit, the plant is not affected by any insects or pests.


If the leaves of your dahlia plant are getting brown, don’t panic. Just try to find the real cause behind it. Try to give the plant all its needs from time to time. This problem can be solved in 80% of cases with proper care and action.

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