The massive May blooms of a lilac can be white, purple, pink, reddish-purple or the most popular color--lilac-lavender. Choose a scented variety and plant near a window or sidewalk where you can enjoy the pleasing fragrance of this shrub. Capable of reaching heights and widths of up to 20 feet where it can look more like a tree than a shrub, you may want to prune lilac to keep it confined to its chosen location.
Prune off spent blooms to encourage new more blooms. Look for suckers, which are sprouts coming up from the roots or a bud at the base of the shrub. Cut weak suckers and snip the top of stronger ones just above a bud to encourage branching.
Prune in March about every five years to help retain shape and height. Select about 1/3 of the oldest branches and cut them to the ground.
Cut overgrown lilac in stages over the course of three years. The first year, in March, use the loppers and cut 1/3 of the oldest (largest) branches to the ground. Cut half of the remaining branches the following March and finish the third year by cutting the remaining branches to the ground. Using this cutting technique allows old branches to continue to produce blooms during the reshaping process.
Prune any weak new growth.