Why Are My Lilac Leaves Turning Brown?

Updated: Jul. 31, 2023

If you're having trouble with your lilac leaves curling or looking brown, our garden expert can diagnose the problem. Plus, find out if deer eat lilacs.

Lilac Leaves Affected by Disease and Drought

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Don’t ignore brown or curling lilac leaves

“My lilac starts off green and healthy, but then the leaves turn brown and it looks as if it’s dying. A couple of weeks later, it looks healthy again. The process repeats three or four times throughout the summer. What’s going on?” —Birds & Blooms reader Robert Snyder

Horticultural expert Melinda Myers: Those symptoms could be a response to periods of drought. Closely examine the lilac leaves throughout the season, monitor rainfall and irrigation practices, and see if there is a correlation between the two. A nutrient deficiency also causes leaf discoloration. It usually expresses itself in a certain pattern or portion of the plant.

If this sounds like a possibility, have your soil tested to help you determine which, if any, fertilizer is needed. Nutrient deficiencies also occur when the soil is too wet or too dry. In these cases the plants are unable to absorb nutrients from the soil. Proper watering helps if this is the cause.

Here’s how, and when, to prune lilacs.

Curling Lilac Leaves

“The leaves on my lilac curl up and it has never fully flowered. What might be wrong?” —Birds & Blooms reader Susan Hartzell

Melinda: Lilac blight caused by bacteria may lead to curling leaves. Brown blemishes or lesions may appear on the leaves and new shoots. Pruning out infected branches below the diseased portion is the only control. Be sure to disinfect your tools with alcohol or a disinfectant spray between cuts.

If leaves are curled but green and free of spots, it may be a root issue caused by too much or not enough water. Try watering thoroughly and less often to encourage deep roots. Insufficient sunlight, overfertilization or pruning any time other than right after the lilac flowers (or when it should have flowered)  can prevent it from blooming the next year.

Is your lilac bush not blooming? Find out what to do.

Do Deer Eat Lilac Leaves?

275833531 1 Donald Turner Bnb Bypc 2021 1Courtesy Donald Turner
Eastern tiger swallowtail butterfly on lilac bush

“Three of my five lilac bushes have missing, stripped leaves. I’ve read that deer avoid lilac, so what could be causing it?” —Birds & Blooms reader Beverly Calderoni

Melinda: No plant is 100% deer proof. Deer tear plants when browsing, leaving ragged tissue behind. On the other hand, rabbits have sharp teeth that make a clean cut like a bypass pruner. They can only eat leaves that they can reach, typically within 3 feet of the ground. Squirrels may rip off the bark, removing leaves at the same time.

While scare tactics may work to keep certain kinds of animals away, most urban and suburban wildlife have become used to people, making this a less-successful option. Consider applying a repellent, such as Plantskydd, that’s labeled for controlling deer, squirrels and rabbits while also being resistant to rain and snow. That way, you will need to apply less often.

Next, discover the top 10 bushes with purple flowers.