The lilac is prized for its purple-pink blossoms, which bloom abundantly in spring. The flowers are aromatic, pleasing both sight and smell when in bloom. Lilac bushes require minimal maintenance, though pruning them yearly helps them to maintain their shape. Lilacs flower on two- to three-year-old wood, so new plantings require little pruning, though older bushes may need further trimming. The best time to trim lilac bushes is immediately after flowering in the spring or early summer.
Pinch off the top 1/2 inch of each branch the first year after lilac is planted. This encourages branching and fuller growth on the bush.
Cut off dead or damaged branches with sharp pruning shears. Cut above the nearest leaves on the healthy part of the branch or completely sever dead branches where they join the nearest main stem.
Look for flower buds on the old branches to determine which are no longer producing blooms. Flower buds form in pairs where the leaves join the stem on two- to three-year-old wood.
Trim off the old branches that are no longer producing flower buds. Avoid pruning young branches that haven't matured enough to bud. These appear greener and less woody than the older branches.