Why Are My Lilac Leaves Turning Brown? (Revealed)

In this article, why are my Lilac leaves turning brown, we will describe everything about Lilac’s life cycle. We will try to process the life cycle of the plant and the main climatic and pedological characteristics that this plant tolerates.

By getting acquainted with the main parts, we will be able to guess what problems cause brown leaves. We will try in a separate subsection to describe the most common issues that this plant may encounter, their symptoms, and methods of solving them.

All About Lilacs

why are my lilac leaves turning brown

Lilac (lat. Syringa) belongs to the olive family (Oleaceae) and is widespread in Europe and Asia. Lilacs can be classified as deciduous shrubs or small trees, usually 2 to 10 meters high, with trees 20–30 cm in diameter. The leaves are heart-shaped or lanceolate in opposite directions (occasionally in the vertebrae of trees). They bloom in spring.

The flowers are purple (often light purple or lilac), but white, golden yellow, and pink specimens grow as well. The flowers of some species have a powerful scent, by which they are recognizable. They bloom from spring to mid-summer. The fruit is in the form of a dry brown capsule. The most recognizable lilacs are white flowers that smell irresistibly. They are often placed in decorative bouquets.

1. History

Among all lilacs, the most famous specimen is the Common Lilac (lat. Syringa vulgaris), which originates from the Balkan Peninsula. This specimen grows on rocky hills. It is produced around the world as an ornamental and aromatic plant. It is inhabited in other parts of Europe (including the UK, France, Germany, and Italy) as well as much of North America.

In addition to the decorative properties of some lilacs, Common Lilacs are also used as medicinal plants. The flowers are used for coughs, kidney stones, diaphoretics, antimalarials. The leaves are used to treat ulcers, tuberculosis, rheumatism, and the like. Due to its alkaloid properties that can harm humans, care must be taken when using it internally.

2. Temperature and Humidity

Lilac shrubs are a plant that does not tolerate warmer and wetter climates. They are most accustomed to climates with moderately warm and not too hot summers.

These are shrubs that can withstand temperatures that drop below zero. It does not tolerate high humidity, which causes various plant diseases. Although it takes low temperatures well, it is advisable to protect it from solid frosts and wind gusts that can damage it.

3. Light

Lilac is a shrub that belongs to the category of full-day plants. In translation, this means that they require a minimum of six to eight hours of light during the day for their growth and development. They can tolerate soft shade or climates with less daylight but this will affect flowering.

4. Water

Lilac shrubs like moderate soil moisture. Young plants will need to be watered occasionally until they form a deep root system, while for adult lilac plants, rainwater alone will suffice. During the period of drought, it is desirable to provide water to the plants so that they do not dry out. Also, the root does not like excessive moisture, as it inhibits oxygen uptake and suffocation occurs.

5. Soil

Lilacs can thrive on various soils, but on quality soils, they achieve by far the best results. These shrubs thrive best on deep, loose soils rich in organic matter. They also prefer well-drained soils with no water, with a neutral pH.

6. Fertilizer

Additional organic and mineral fertilizers will significantly improve our lilacs. The best way of fertilizing is the one that is done according to the pedological analysis of the soil, but if we are not able to do this beforehand, it would be best to take specialized fertilizers of this type of plant. Top-dressing would be desirable a couple of times during the year, especially if the soil is poor in nutrients.

7. Pruning

Pruning is a crucial job for growing lilacs. Namely, with this method, we achieve:

  • A growing form of the plant itself
  • We thin the canopy to achieve better ventilation
  • We prevent the appearance of diseases such as powdery mildew that occur on unventilated leaves full of moisture
  • We control the height and width of the plant
  • We remove damaged and diseased branches

Pruning is a necessary method during the cultivation of lilacs can have negative results if we overdo it. It is essential to carefully and systematically cut the branches to not leave without too much canopy. When pruning, you should take care not to damage the plant itself.

8. Propagation

Lilac is a shrubby plant that spreads quickly. Namely, these shrubs can be propagated by root cuttings to an entirely new place. You can dig up the bush’s root and gently remove one of the cuttings, which you can transfer to a new location. The cuttings you have carefully removed should be buried in soil rich in humus. This is an efficient and inexpensive way to propagate lilacs.

Why Does Lilac Leave Turning Brown?

lilac leaves turning brown

Suppose you notice that lilac leaves are turning brown. No matter how frequent it is in the region, it does not mean that it is not dangerous, nor that your Lilac is safe. The most common reason why this problem occurs is the appearance of bacterial disease, which is often manifested by the arrival of leaves turning brown. In the following, we will try to explain what it is about.

Bacterial disease causes the appearance of brown spots on leaves and stems. The newly formed areas become more significant over time, and later the entire leaf becomes brown and curled. With a significant infestation, lilac flowers turn brown.

It is complicated to cure the plant itself when this disease occurs. The best results are achieved by applying agro-technical measures such as pruning diseased and infected parts and applying copper-based fungicides. It is essential to maintain the hygiene of the plant and the tools with which this process is performed since the pathogen is very easy to spread. All devices used when pruning diseased branches should be disinfected in an alcoholic solution at each cut. Two to three applications with a fungicide every seven to ten days are recommended.

Once a problem arises, the best result is to stop further spread. The best method of combating this pathogen is in the prevention itself, which is reflected in the measures before the appearance of the disease, and these are:

  • Proper pruning to improve ventilation
  • Adequate plant nutrition that builds plant immunity
  • Good planting distance between each plant
  • Preventive treatment with biological and organic plant protection products
  • Maintaining the hygiene of lilacs

Other Problems That Can Cause Lilac Leaves To Turn Brown

Although the appearance of brown leaves is attributed to bacterial infection in most cases, the problem may be in other external factors. We will briefly explain other factors that are less likely to cause.

Many insects often attack lilacs from different families that feed on the plant’s leaves. With their suction device, they often extract nutrients from the leaves, causing the leaves to twist and dry. The leaves may turn brown due to a lack of nutrients in the leaf.

Lilac leaves can also turn brown due to environmental factors if it is a year that is in deficit or surplus with precipitation. The leaves may turn brown due to a lack of excess moisture in the soil. Also, if the pH reaction of the ground is not around neutral, the same problem can arise.

Another problem that can cause brown leaves is improper fertilization of lilacs. If these shrubs lack phosphorus and potassium during flowering, a brown color may appear on the leaves. Be careful when fertilizing because too much can damage the plant.

Also, inadequate external factors in which our shrubby plants grow can cause brown leaves. Namely, all those factors that do not suit lilacs can cause this problem. Strong frosts and long cold periods, too much sun, and strong wind gusts are some of the many factors contributing to this problem.


Q: Why are my lilac leaves turning brown and curling?

A: The answer to this question lies in several potential plant disorders. The most common reasons for brown leaves and twisting are:

  • In the first place, the plant diseases of lilacs such as powdery mildew, bacterial infection, or lilac blight.
  • In the second place, the second most common reason is the attack of various insects that secrete natural juices from the leaves.
  • In the third place can be all those ecological extremes that do not suit the plant, such as excessive humidity, lack of light, excessive frosts, etc.

Q: How do you treat lilac blight?

A: The most common reason for the appearance of brown and shriveled leaves is lilac blight. If there has already been an infection on the plants and the appearance of the first symptoms, it is necessary to separate all the infected parts from the plant and then burn them. After pruning all infected parts of the plant, it is recommended to treat with copper sulfate on a couple of occasions.

The best results are achieved in the first preventive effect on the plant, such as the correct assembly of plants per unit area, maintaining airy space inside and between plants, maintaining the hygiene of lilacs, proper fertilization, and the like.

Q: Do lilac trees need a lot of water?

A: Lilacs are plants that like moderate soil moisture, and we should try to respect this. Young plants require more moisture due to the shallow root system, while mature plants draw additional water from the deeper layers of the soil.

The temperature of the environment largely depends on the frequency of watering. If it is a long period of drought, we will have to water our lilacs additionally.

Q: How do you care for a lilac tree?

A: Lilac is a plant that does not require too much attention for its growth. In addition to the essential climatic and pedological characteristics it requires (moderate heat, eight hours of sunlight, moderate humidity), it tolerates pruning well. With this technique, we can directly affect the health of these shrubs and their decorative appearance. It is necessary to maintain moderate soil moisture in these shrubs and fertilize them.


We have tried to describe all the main characteristics of Lilac’s, origin, climatic and pedological factors of cultivation, and the most common problems that can arise when lilac leaves turning brown arises.

We hope we have helped you answer the question of why Lilac leaves turn brown. Described are the five most common reasons why brown leaves occur, their symptoms, and treatment methods. We hope you will react in time and save your beloved lilac bushes.


Ask Extension: My lilacs seem to be dying. What can I do?

Lilac: An old-fashioned, favorite shrub – MSU Extension

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