Asked September 22, 2021, 9:33 PM EDT
Dakota County Minnesota
You are probably going to have to sacrifice blooms for next spring. However, you can trim them back to the four/five feet but I also recommend that you cut out 1/3rd of the oldest, thickest stems right to the ground. Those old stems do not bloom well and removing them will encourage new growth from the ground level. After the blooms fade the following year, trim the stems back some and again cut out another 1/3rd of oldest stems. Repeat the following spring and your lilacs will be like new young shrubs.