Gardening: How to Prune Lilacs

Wait until mid- to late summer to prune the lilacs, as soon as the flower blooms fade. You can prune later if desired; however, you will remove the buds that produce flowers the following year.

Grasp the base of each wilted flower and trace the stem back to where you see two side shoots emerge from the stem. Cut the flower off using hand pruners to deadhead the stem. Repeat to remove all other dead flowers.

Look closely at the stems of the lilac bush, holding them back from the bush if needed. Locate any that are diseased or that are brown with no foliage, meaning they are dead. Trace the vertical stems back to the ground and snip them off using hand pruners.

Identify any remaining limbs that are broken, bent or otherwise misshapen and prune them off in the same manner using the hand pruners.

Examine the top of the plant and compare the stem heights until you locate the tallest ones. Trace one of the tall stems back to the ground and cut it off using the hand pruners. Repeat the process to remove 1/3 of the tallest stems so that there is at least 1 to 2 inches of space between all remaining stems.