Fragrant lilacs are a highlight of late-spring gardens. Many homeowners are familiar with the common or French hybrid lilacs (Syringa vulgaris), the most commonly planted type of lilac for generations. These large shrubs bloom for two weeks in mid-May in New England, in early May in the Mid-Atlantic and in April in the South. There are many types of lilacs and by choosing different varieties, gardeners can have lilacs in bloom for more than a month.
Blooming seven to 14 days before common lilacs, the early lilac (S. oblata) is a 10- to 12-foot shrub with lilac flowers and good purple-red, fall leaf color. Used primarily as a parent plant for developing hybrids, it may be difficult to find. The early lilac is hardy only in U.S. Department of Agriculture Plant Hardiness Zones 3 through 6. Another early bloomer is S. x diversifolia, a hybrid lilac with white or pale blooms and deeply lobed leaves. It also blooms a week or two before the common lilac.
The Main Show
Common lilacs may be the most familiar lilac, but other species bloom at the same time. The Chinese lilac (S. chinensis) is an 8- to 15-foot, rounded shrub with purplish-lilac flowers and a more refined, graceful habit than the common lilac. It's hardy in USDA zones 3 through 7. The cutleaf lilac (S. laciniata) grows just 6 to 8 feet high and wide with small, fragrant, lilac flowers. Hardy in zones 4 to 8, it's a good choice for warm parts of the country where many lilacs struggle.
Extend the lilac show by planting the dwarf Korean or Manchurian lilac (S. patula), which blooms one to two weeks later than S. vulgaris. Miss Kim is a popular cultivar. It's hardy in USDA zones 3 through 8. Other late bloomers include the Chinese tree lilac (S. pekinensis) and the Japanese tree lilac (S. reticulata), both of which bloom two to three weeks after common lilacs. These large lilacs grow 20 feet or more and are covered with fragrant white flowers. Both species are hardy in zones 3 through 7.
A recent development is the introduction of several reblooming lilac cultivars. Josee has light lavender-pink flowers, while Bloomerang has deep purple blooms. Reblooming lilacs first flower at about the same time as common lilacs, then bloom again in late summer as the weather moderates. Hardiness depends on the cultivar.