Lilacs are popular shrubs in my area of the Midwest. The term French Lilac is often used to refer to modern double-flowered cultivars, thanks to the work of prolific breeder Victor Lemoine.
Lilacs flower on old wood, and produce more flowers if unpruned. If pruned, the plant responds by producing fast-growing young vegetative growth with no flowers which makes it a great hedge. In an attempt to restore removed branches; a pruned lilac often produces few or no flowers for one to two years, before the new growth matures sufficiently to start flowering. Unpruned lilacs flower reliably every year. Despite this, a common fallacy holds that lilacs should be pruned regularly. If pruning is required, it should be done right after flowering is finished, before next year's flower buds are formed.
Lilac bushes can be prone to powdery mildew disease, which is caused by poor air circulation. Fox Hill Nursery in Maine sells over 90 varieties of lilacs.