Prune a lilac bush by removing one-third of the stems each year, trimming away dead or damaged limbs, removing suckers, pruning awkward and thick branches, deadheading the bush, and shaping the plant. Pruning shears are needed for this task.Continue Reading
After the lilac bush flowers, cut back one-third of the stems. Each year, maintain the size of the bush, and cut back the stems accordingly. It is not always necessary to prune one-third of the stems.
Remove all dead, damaged and diseased branches from the bush on a regular basis.
Remove all suckers and thin, twiggy branches.
Remove all branches that rub against others or are awkwardly positioned. Prune all branches that are bigger than 2 inches in diameter.
Deadhead faded lilac flowers, as this encourages the plant to grow more buds. Only deadhead the flowers during the first few years of the life of the bush.
Shape the lilac bush by regularly pruning both old and new growth. When pruning new growth, cut the branches down to the nearest outward-facing bud. Keep only eight to 12 of the stems at any given time.