Why is my lilac bush turning brown? (And How to Save It!)

Oh, that moment when you look out at your lovely lilac bush and expect to see the fragrant blooms and lush green foliage, but instead you see brown. You might be asking, “What the heck is going on?” when you see this. It’s something that can make any plant parent gasp.

So, what is making my lilac bush turn brown? The first thing you should know is that browning is not an illness or condition in and of itself. Your lilac is trying to warn you that something isn’t quite right. The browning could be an indication of problems with watering (too much or too little), a fungal or bacterial disease trying to take hold, bugs that don’t belong there establishing themselves at home, stress from the plant’s surroundings, or even just normal processes.

Don’t worry, we’re here to assist you figure out what’s wrong with your plants! We’ll talk about the most common reasons why your lilac might be turning brown, how to figure out what’s wrong, and how to get it back to its healthy, bright self in this article. Let’s work together to find this out. Keep reading!

Watering Problems: Is There Too Much or Too Little Water?

Before we get into more complicated problems, let’s start with the basics. Most of the time, the leaves turning brown is because they weren’t watered properly. Like Goldilocks, lilacs don’t like it too moist or too dry.

Underwatering Stress: Is Your Lilac in Need of Water?

Your lilac’s leaves will definitely tell you if it isn’t getting enough water.

• Symptoms: You might initially notice that the leaves are drooping or wilting. Then they can turn yellow, then brown, and often become dry and crunchy when you touch them. This browning often starts at the very tips or edges of the leaves and moves within. You can also notice that the whole plant droops and that new development slows down or stops.
• How to Check: The easiest way to check is with your finger! Put your finger around two to three inches into the ground toward the base of the lilac. Your plant is probably thirsty if the soil feels dry at that depth.
• Why it happens: This can happen if it doesn’t rain enough (especially during hot, dry spells), if you don’t water it deeply or often enough, or if you plant your lilac in very sandy soil that drains fast and doesn’t hold onto moisture for long.

Overwatering and Root Rot: Are you giving your lilac too much water and causing root rot?

It may seem strange, but too much affection in the form of water can be just as bad, if not worse, than not enough.

• Symptoms: Overwatering a lilac makes its roots unable to breathe, which causes root rot. The leaves could turn yellow and then brown, but they could not be crispy; they would feel soft or even mushy. The leaf could start to turn brown in the middle, show up as blotchy areas, or the whole leaf could change color. You might also notice that the plants aren’t growing as quickly, and in more advanced cases of root rot, the soil might even smell bad, like a swamp.
• How to Check: To check, the earth will always feel wet, muddy, or waterlogged, not just moist. If you look closely at the roots, good lilac roots are usually solid and white. If they are rotting, they will be brown or black, squishy, and mushy, and they may fall apart easily.
• What causes it: This happens a lot in soil that doesn’t drain well, like heavy clay that traps water like a sponge. It can also happen if you water your lilac too often or if it is in a pot that doesn’t have enough drainage holes (most lilacs are grown in the ground).

Getting the irrigation right is the most important thing for a healthy lilac. If these descriptions don’t quite match what you’re seeing, or if you’ve checked your watering and are sure it’s not the problem, let’s look at some other things that could be causing the problem.

Detectives of Disease: Finding the Pathogens That Make Lilacs Change Color

Unfortunately, like other plants, lilacs can sometimes fall victim to numerous illnesses, many of which can cause browning of the leaves, stems, or blooms. Let’s look into some of the common suspects:

Bacterial Blight (Pseudomonas syringae)

This one can be especially disappointing because it often hits nascent growth.

• Symptoms: Picture those new flower buds and shoots that you were so pleased about now looking sad, wet, and then quickly turning dark brown or even black. That’s a clear sign. Leaves can get dark, uneven areas that may eventually dry out and fall off, making them look like they have “shot holes.” You could also detect dark lines on the new twigs.
• Conditions that help it: Bacterial blight enjoys cool, moist spring weather, which is when your lilac is trying to look its best. Watering from above that keeps the leaves wet for a long time can also help it grow.

Fungal Leaf Spots, like Septoria and Phyllosticta

There are a number of different fungus that can make lilac leaves spotty.

• Symptoms: You’ll notice clear dots on the leaves as a sign of this. The color of these patches can change; they might be brown, tan, or even purple, and sometimes they have darker edges. As the condition becomes worse, these spots may get bigger and merge, making the tissue brown in more areas. In very bad infections, the leaves that are affected may turn yellow and fall off too soon.
• Conditions that help it grow: These fungal spores do best in humid conditions and when the air around the plant doesn’t move well.

Powdery Mildew

This disease is well-known for making things look white and powdery, but a severe or late-stage infection can undoubtedly make things brown.

• Symptoms: It usually starts as a white or grayish powdery coating on the tops of leaves, and sometimes on stems and blossoms. If the problem gets worse and isn’t fixed, the leaves that are impacted may turn yellow, then brown, become misshapen, and fall off the plant sooner than they should.
• Conditions that make it more likely: Powdery mildew is more likely to show up when the humidity is high (particularly at night), the temperatures are moderate during the day, and there isn’t much air circulation or shade.

Verticillium Wilt

This is a more deadly fungal disease that lives in the soil and can harm many types of plants, even lilacs.

• Symptoms: One of the most obvious indicators is that the leaves start to wilt and turn brown or yellow, usually on just one side of a branch or in one area of the plant, while other parts still look healthy. If you cut into a branch that was impacted, you might detect reddish or greenish streaks in the wood immediately below the bark. Sadly, Verticillium wilt can kill the plant over time.
• Conditions that help it: The fungus resides in the soil and can get into the plant through its roots, usually through wounds from farming or worms. It blocks the plant’s tissues that carry water.

Armillaria Root Rot, often known as Oak Root Fungus

Armillaria is another dangerous fungus that lives in the soil and can cause a steady deterioration.

• Symptoms: You might witness a slow reduction in the lilac’s vigor, with leaves yellowing, then browning and drooping, leading to branch dieback. If you can see it, the presence of white, fan-shaped fungal mats (mycelium) immediately below the bark at the base of the plant, near the soil line, is a major symptom of the disease. In the fall, groups of mushrooms that are the color of honey may also grow around the base of the lilac that is sick.
• Conditions that make it more likely: This fungus commonly attacks plants that are already under stress for other reasons. It can spread via the soil from infected tree roots or ancient stumps.

If you think your plant has a disease, taking clear pictures of the symptoms can be very helpful if you need to talk to your local nursery or extension office for a diagnosis.

Unwanted Guests: Pests That Stress Your Lilac

Sometimes, the browning on your lilac isn’t because of a disease; it’s because little bugs are eating it or making it stressed. Let’s take a look at some common pests that attack lilacs:

Lilac Borers (Podosesia syringae)

These are the larvae of a clearwing moth, and they can do a lot of harm.

• Symptoms: One of the most important signs is that individual canes or whole branches suddenly start to wilt and become brown. If you look closely at the afflicted stems, you might discover small holes in the bark, possibly with sawdust-like frass (their excrement) nearby. The bark may also look bloated or broken in places where borers are working.
• Type of damage: The larvae dig into the woody stems and branches, blocking the flow of water and nutrients. This causes the dieback and browning you notice.

Scale bugs, like oystershell scale

These little bugs don’t move around much, so it’s easy to miss them until there are a lot of them.

• Signs: You’ll see little, hard or waxy bumps (the scale insects themselves) that are stuck to the stems and branches. They often seem like little brown or gray spots or tiny oyster shells. A lot of bugs can make the lilac’s leaves become yellow, then brown and wilt, and they can even kill the branches. These bugs suck sap, which explains why. You might also see a sticky fluid on the leaves or stems called honeydew. This might cause black sooty mold to bloom.
• Type of damage: They suck the sap out of the plant, which makes it weaker over time.

Spider Mites and Aphids

Even though these common garden pests don’t necessarily cause widespread browning on their own, a lot of them can stress your lilac, which can cause the leaves to turn yellow, bend, and eventually fall off.

• Signs:
  • Aphids are little, pear-shaped bugs that are usually green, black, or brown. They like to hang out in groups on new growth and the bottoms of leaves. They make leaves coil, pucker, or change shape. They also pee out sticky honeydew, which can bring in ants or cause sooty mold, just like scale.
  • Spider mites are quite little (you might need a magnifying lens to see them well) and do well in hot, dry places. A delicate stippling (little yellow, white, or bronze dots) on the leaves is usually the first indicator. You might also see very thin webs, especially on the backs of leaves or where leaves meet stems. Leaves that are heavily affected can turn brown or bronze, dry up, and fall off too soon.
• Type of damage: Aphids and spider mites suck sap from plants, taking away important nutrients and water and causing the plant to become stressed and die.

Environmental Stress: When the Place and Conditions Make Things Brown

It’s not always a living pest or disease that makes your lilac turn brown. Sometimes it’s something in its environment or a stressor associated to how you care for it or where you keep it.

Shock from Transplanting

It’s normal for a lilac to turn brown after you plant it or move it.

• Symptoms: Some leaves may wilt, turn yellow, and ultimately turn brown. For a while, the plant might just appear sad in general.
• Why it happens: Digging up a plant, disturbing its roots, and then getting used to a new soil and position is hard for any plant. It takes time for the roots to grow again and be able to absorb water and nutrients.

Stress from heat and sun

Lilacs like full sun most of the time, although they can get sick in particularly hot places or during very hot summer heatwaves.

• Symptoms: You might see browning or even bleaching (whitening) mostly on the edges of the leaves or on the areas of the leaves that get the most direct, intense sun. The areas that are impacted may look dry and crispy.
• Why it happens: The plant’s roots can’t take up enough water quickly enough to cool its leaves enough when it’s really hot, or the sun’s direct rays are literally burning the leaf tissue.

Frost Damage (Frosts in Late Spring)

An unexpected late frost can ruin your lilac just as it’s starting to grow its new leaves and blossom buds in the spring.

• Symptoms: After a frost, the fresh, soft growth (leaves and flower buds) may typically become black or dark brown and die back nearly overnight.
• Why it happens: Ice crystals accumulate inside the cells of this fragile new growth, breaking the cell walls and hurting the tissues.

Lack of Nutrients

Not very often, but not very often, a lack of some important nutrients might cause particular areas to turn yellow (chlorosis). If this happens too often and isn’t fixed, the affected tissues can turn brown and die.

• Symptoms: The pattern is the most important thing about the symptoms. For instance, iron shortage commonly causes fresh growth to have fading leaves with very green veins (interveinal chlorosis). If a plant doesn’t get enough magnesium, the edges of older leaves may become yellow and ultimately brown.
• Why it happens: The soil may not have enough of the nutrients the plant needs, or the plant may not be able to absorb them well, possibly because the soil pH is wrong.

Chemical Damage or Herbicide Drift

Things happen, and sometimes chemicals used nearby can hurt your lilac by mistake.

• Symptoms: those typically suddenly twist, curl, cup, spot, or turn brown, and they often do so in a way that seems like spray drift (for example, impacting one side of the plant more than the other or those that were most exposed).
• Why it happens: Plant tissues can be damaged by accidentally coming into contact with herbicides (weed killers) used on lawns or in neighboring regions, or by other powerful chemicals.

Soil that isn’t compacted well or doesn’t have enough oxygen for the roots

Roots that are healthy need oxygen to work right.

• Symptoms: This usually causes the health of the plants to get worse overall, with poor growth, smaller leaves, and eventually yellowing and browning of the leaves.
• Why it happens: The soil has very little air space because it has been packed down a lot (from foot activity, construction, or just being very heavy clay). This stops roots from growing and takes away the oxygen they need to live and get water and nutrition.

Are the browning and natural transitions normal?

Before you freak out, think about if the browning you perceive might just be a typical part of your lilac’s yearly cycle or the process of getting older.

Leaf Drop at the End of the Season

Lilacs, like many other deciduous shrubs and trees, lose their leaves in the fall to get ready for winter hibernation.

• What you will see: In the fall, when the days become shorter and the weather gets cooler, your lilac leaves will naturally start to turn yellow or brown before they fall off the branches. This is completely normal and nothing to be concerned about!

Old Wood and Dead Flowers

Lilacs also get older on their own.

• What you will see:
  • Old Wood: The older, heavier woody stems in the middle of a mature lilac bush may not be as prolific over time and may naturally die back, becoming brown. This is how the plant gets fresh life.
  • Spent Flowers: After your lilac blooms in the spring, the individual flower trusses will gradually fade, become brown, and dry up. This is also quite typical. Many gardeners “deadhead” or take off these spent flower clusters to make the plant look nicer and occasionally to help it bloom better the next year (though this isn’t necessary for the plant’s health).

To tell the difference between normal browning and problematic browning, you need to look at the plant’s overall health and the pattern and timing of the browning. It’s probably usual for all the leaves to change color at the same time in the fall. It’s normal for wasted flowers to become brown after they bloom. If you detect brown spots on new growth in the spring, along with wilting, spots, or other strange symptoms, though, you should look into it more.

How to Figure Out What’s Wrong with Your Browning Lilac

We’ve talked about a number of possible suspects, so let’s move on. So, how do you know which one (or maybe even a mix of them) is hurting your lilac? Put on your plant detective hat and start looking closely. Here is a short list to help you:

Look at the pattern of browning:

• Where on the plant is the browning happening? Is it predominantly on the fresh, soft leaves or on the older, tougher ones?
• Is it more on the tips or margins of the leaves, or is it in the middle, or does it look like separate spots?
• Is it only harming one or two branches, a large part of the plant, or the complete bush?
• Are the blooms harmed too, or only the stems and leaves?

Look at the moisture in the soil:

• Get your hands dirty! Put your finger a few inches into the ground next to the base of the plant. Is it completely dry? Is it damp and wet? Or is it pleasant and moist, like a sponge that has been wrung out?

Take a close look at the stems and branches:

• Check the bark for any holes, which could mean borers.
• Do you observe any cankers (sunken, discolored spots), strange bumps, or cracks on the stems?
• Are there any little lumps that don’t move that could be scale bugs?
• If you scrape off a little bit of the outer bark (slowly and just on a small, afflicted branch if necessary), is the wood underneath healthy green or white, or is it brownish or streaked, which could mean it has a wilt disease?

Take a Close Look at the Leaves (Both the Top and the Bottom):

• Do you observe any fine webbing? This could mean that you have spider mites.
• Do you see any bugs, like aphids, on fresh growth?
• Is there a white, powdery substance (powdery mildew)?
• Are there identifiable patches with clear edges, or is the browning more spread out?

Think on what’s happened recently and what’s going on in the environment:

• Did you just relocate or transplant the lilac?
• Has there been any really bad weather lately, such a sudden heat wave, an unexpected late frost, a drought, or a long stretch of very heavy rain?
• Has someone applied herbicides or other chemicals on your lawn or in your garden nearby that might have blown onto the lilac?

Look back at how you’ve been taking care of things lately:

• How often and how much have you been watering it?
• Did you give it any fertilizer lately? If so, what did you use and how much did you put on?
• How did you prune it the last time you did?

You can frequently limit down the options a lot and get a much better picture of what’s causing the browning by going through these questions in order and thoroughly looking at your plant.

The Road to Recovery: Ways to Help and Ways to Avoid Problems

When you know what’s making your lilac turn brown, you can begin to help it get better and stop the problem from happening again. Here are some broad fixes and ways to stop problems from happening, many of which are just good lilac care:

How to Water Your Plants Correctly:

• Water established lilacs deeply but not very often, letting the top few inches of soil dry out between waterings. During dry seasons, it’s generally better to soak the ground well once a week than to sprinkle it lightly and regularly.
• Water the base of the plant to keep the leaves dry. This helps stop a lot of fungal illnesses.
• Young lilacs that have just been planted will need to be watered more often until their roots are strong.

Making the soil drain better:

• If your soil is thick clay and stays wet, add a lot of organic matter, like compost, to make it better at draining and holding water.
• If your drainage is really bad, you might want to make raised beds or berms for your lilacs.

Taking care of diseases:

• Sanitation is really important! Cut off any leaves, stems, or branches that are plainly sick right away. Make sure to cut into good wood, deep below any evidence of illness that you can see.
• If you think you might have a contagious sickness, make sure to clean your pruning tools (such with a 10% bleach solution or rubbing alcohol) between cuts to keep it from spreading.
• Give your lilac enough room and, if necessary, prune out some of the thick foliage on the inside to let more air flow around it.
• Do not water from above.
• When everything else fails, you can apply the right fungicides to get rid of some fungal diseases, such powdery mildew or severe leaf spots. But you should always try cultural controls first. Carefully follow the instructions on the label.

Controlling pests:

• A powerful spray of water from the hose can occasionally get rid of pests like aphids or small scale infestations.
• Insecticidal soaps and horticultural oils can kill a lot of soft-bodied bugs, like aphids, spider mites, and scale crawlers (the immature, moving stage). Follow the directions on the label, which normally say to do it when the weather is mild.
• The easiest way to get rid of lilac borers is frequently to cut out and remove infested canes below where the borers are active. Keeping plants healthy can also help lilacs stay strong.
• Don’t use broad-spectrum pesticides in your garden to attract helpful creatures like ladybugs, which devour aphids.

Keeping safe from environmental stress:

• Put 2 to 3 inches of organic mulch around the base of the lilac, but keep it a few inches away from the stem. This will help keep the soil moist, keep the temperature of the soil stable, and keep weeds from growing.
• When there are really hot days, giving weak plants some shade in the afternoon can help keep them from getting sunburned.
• If a frost is expected in late April, you can try covering young, delicate lilacs with an old sheet or frost cloth overnight.

Good Ways to Keep Things Clean:

• In the fall, pick up and throw away any leaves and trash that have fallen around your lilac. This is because many disease spores and pest eggs can stay alive in this material over the winter.

How to Prune Right for Health and Strength:

• Pruning your plants lightly and regularly can help keep the structure healthy and the air flowing. Most of the time, the best time to prune lilacs is just after they bloom in late spring. This is because they set their buds for next year’s flowers on old wood over the summer.

When to think about getting rid of:

• Unfortunately, a lilac bush can’t always be salvaged if it is really sick with a disease like advanced Verticillium wilt or has a lot of borers. If the plant is mostly dead or could spread illness to other healthy plants, taking it out might be the best thing to do.

Conclusion: How to Save Your Lilac (or Keep It Healthy!)

It’s understandable to be worried when your lovely lilac bush turns brown, but as we’ve seen, it’s usually a problem that can be fixed. The first and most important thing you need to do to cure your lilac shrub is to figure out why it is going brown.

You can typically figure out what’s wrong with your plant, or at least narrow it down a lot, by carefully watching it, thinking about its surroundings, and going over how you care for it. A little change to how you water, some focused insect treatment, or some smart pruning to fight a disease can all make a big difference if you do it at the right time and with the right care.

Don’t give up! You can fix a lot of browning problems, and with a little knowledge, you can frequently bring your lilac back to its gorgeous, fragrant self or keep your healthy lilacs that way for many years to come. Enjoy your gardening!

Common Questions About Browning Lilac Bushes

Why are the ends of my lilac leaves getting brown and crispy?

This common sign usually means that the plant isn’t getting enough water or that the humidity is too low. If you’ve been giving your plants too much fertilizer, it could also be a sign of fertilizer burn. If the plant is getting too much direct, intense sun without enough water, it could also be a sign of sun scorch. The first thing you should do is check the moisture in your soil.

Can a lilac become better after getting bacterial blight?

Yes, a lilac may often get better from bacterial blight, especially if you catch it early and prune out the sick areas right away and correctly (making sure to cut into healthy wood and clean your pruners between cuts). To assist keep it from coming back, make sure the air surrounding the plant can flow freely and don’t get the leaves wet when you water them. But in really bad circumstances, they might be very bad.

What are those tiny brown bumps on the stems of my lilacs?

Those little brown bumps that are stuck to the stems and branches are probably scale insects. They can also be gray or white. They suck the sap out of plants and can make your lilac weaker over time, which can cause its leaves to turn yellow, die back, and look sickly. Horticultural oil or insecticidal soap will often help, but you need to do it at the right time to get them when they are most vulnerable.

Is it usual for some of the leaves of a lilac to turn brown when you move it?

Yes, it’s usual for the leaves of a lilac to wilt, turn yellow, or turn brown after you move it. People call this “transplant shock.” The roots of the plant have been moved, and it needs time to become used to its new home and learn how to take in water and nutrients again. During this time of recovery, it is important to water the plants regularly (but not too much!) and be patient.

All of a sudden, my lilac bush went brown. What may it be?

If a whole lilac bush suddenly turns brown all over, that’s a serious warning that something is wrong and needs to be looked into right away. This could mean a serious problem, like Verticillium wilt (especially if it started on one side and spread quickly), a big root problem (such advanced root rot from very bad drainage or Armillaria root rot), or maybe even chemical damage from herbicide drift. You should look closely at the plant from the roots to the tips for any signs.