Plant Taxonomy of Lilac Bushes:
Plant taxonomy classifies common lilac bushes as Syringa vulgaris. The cultivar shown in the picture is 'Wedgewood Blue,' sometimes spelled 'Wedgwood Blue.'
Most lilacs are deciduous shrubs. 'Wedgewood Blue' is one variety that has a compact growth habit. But because of the height some varieties attain at maturity, people sometimes refer to them as "lilac trees." They should not, however, be confused with the true "tree lilacs": i.e., Japanese tree lilacs (Syringa reticulata) and Chinese tree lilacs (Syringa pekinensis).
USDA Plant Hardiness Zones for Lilac Bushes:
Characteristics of Lilac Bushes:
'Wedgewood Blue' attains a height at maturity of 6', with a spread equal to that. Flower color is lavender-blue, and the flowers are contained in thick clusters. Blooming time is late spring. The leaves are dark green, but this shrub is grown first and foremost for the fragrance of its flowers and their beauty, not its foliage. One of the most unforgettable aromas of the plant world!
Sun and Soil Requirements for Lilac Bushes:
Grow lilac bushes in full sun. They prefer a rich, well-drained soil with a neutral pH.
Care for Lilac Bushes:
Lilac bushes are prone to powdery mildew disease, so provide good air circulation by keeping their branches pruned. Prune right after blooming is over. In addition to branch pruning, cut the dead flowers off when they're done blooming. This will prevent the seed from forming and thereby promote more profuse flowering the next spring.
Uses in Landscape Design:
Lilac bushes are attractive enough to be treated as specimens. They are also often planted in rows along property borders and pruned into hedges.
It is beyond dispute that the outstanding quality of many of these plants is the smell of their flowers (I say "many" because not all types are equally fragrant; grow Syringa vulgaris when in doubt if smell is your main interest). They are among the most fragrant flowers that I know of. If you grew up smelling them every year as spring begins to yield to the warm nights of summer, then you're probably spoiled for life!
More on Lilac Trees:
True "tree lilacs" (Syringa reticulata and Syringa pekinensis) bloom a bit later than lilac bushes. Their blooms are white, and they're not as aromatic as the flowers of Syringa vulgaris and other lilac shrubs. But the tree lilacs do have an attractive bark, especially the Chinese tree lilac, which has a shedding bark a la the paper birch (Betula papyrifera).