Lilac doesn’t look right after pruning - Ask Extension
Hello, I pruned the lilacs pictured in early spring. These are mature shrubs that were about 6’ tall. They were starting to get sparse growth nea...
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Lilac doesn’t look right after pruning #907673
Asked June 28, 2025, 10:11 PM EDT
Hello, I pruned the lilacs pictured in early spring. These are mature shrubs that were about 6’ tall. They were starting to get sparse growth near the bottoms. They have been regularly sheered. I used the principle of thirds. Taking out some of the oldest canes and bringing the height down by a third, going forward for two to three years. As you can see one of the shrubs grew back normally, but the others have small leaves on the branches. This is a customer of mine. Please let me know if there is anything that I can do to help these lilacs survive and if they don’t how much is my pruning a factor. There were also birds nest evergreen shrubs in front of the lilac that did not make it over the winter. Thanks so much! Suzan
Hennepin County Minnesota
Expert Response
Many trees and shrubs winter killed. The 40 mph mile an hour north winds and no rain were largely responsible.
Looking at the photo the lilac with a little more shade is doing fine, the lilac that is struggling is in full sun with a stucco wall deflecting heat and rock mulch underneath that stores heat. It is cooking during very hot days. It may need water as often as twice a day when temps are in the 90’s. Soil moisture needs to be checked before watering and if the soil is dry at a depth of 2-4 inches it needs more water. Overwatering is worse than under. Root rot from too much water is often fatal. Enough water will help its recovery. Pruning made it loose more water for a couple of days so aggravated the drought for it. Your pruning practices are fine, the weather unfortunately, has complicated care.
https://extension.umn.edu/news/taking-care-your-lilacs
https://extension.umn.edu/trees-and-shrubs/lilacs
Looking at the photo the lilac with a little more shade is doing fine, the lilac that is struggling is in full sun with a stucco wall deflecting heat and rock mulch underneath that stores heat. It is cooking during very hot days. It may need water as often as twice a day when temps are in the 90’s. Soil moisture needs to be checked before watering and if the soil is dry at a depth of 2-4 inches it needs more water. Overwatering is worse than under. Root rot from too much water is often fatal. Enough water will help its recovery. Pruning made it loose more water for a couple of days so aggravated the drought for it. Your pruning practices are fine, the weather unfortunately, has complicated care.
https://extension.umn.edu/news/taking-care-your-lilacs
https://extension.umn.edu/trees-and-shrubs/lilacs
