Raised beds or mounds are good ways to get their roots above damp ground. Watch the planting height when placing lilacs in the ground. Look for a natural flare at the base of the trunks indicating the proper planting height. Lilacs, like most other landscape plants, don't like to be buried too deep. Lilacs need sunlight.
Sunshine is necessary to produce the energy needed for flower production.
The dwarf shrub types are an exception and will flower in partial shade. Aside from sunlight and drainage, lilacs are tolerant shrubs. Pruning Pruning is a lifetime activity for lilacs. Plants should be rejuvenated each year by selectively removing the oldest trunks at ground level. Rejuvenation pruning is useful for shrubs because it keeps them in a youthful, vigorous growing condition.