Lilacs are some gardener's most beloved spring flowers. These green shrubs with flat, heart-shaped leaves burst alive between Easter and Mother's Day with a profusion of light purple (sometimes white or pink) blooms, filling the air with their distinctive lilac perfume. Cut into bucket-filling bouquets, lilacs bring a welcome breath of spring indoors as well. The most common lilac bushes are hardy in a wide variety of growing conditions.
French Hybric Lilac
The common lilac, or French hybrid lilac (Syringa vulgaris var.) is the most widely grown lilac bush, found in hedgerows and dooryards across North America. The North Dakota State University Extension advises that hundreds of named cultivars of french hybrid lilac are available, in flower shades ranging from deepest purple to white. Most of these will thrive through USDA hardiness zone 2--the farthest northern reaches of the United States and well into Canada. French hybrid lilacs are available through most nurseries and mail order landscaping suppliers; they also send up prolific shoots from the roots of mature, existing shrubs, and most lilac bush owners will gladly share these off-shoots of their prized lilacs.
Korean lilacs (Syringa patula) are more compact, dense lilacs that are often used in more formal landscape plantings where the rambling forms of the common lilac would be a distraction. Korean lilacs bloom slightly later than common lilacs, according to the Cornell Cooperative Extension of Oneida County, and often with tighter blossoms and a tidier growing habit. The most common cultivar of these is 'Miss Kim,' growing to about 10 feet high by 10 feet wide but tolerating shearing back to a smaller desired size. Blossoms on 'Miss Kim' and many other Korean lilacs run a deeper violet color than those on french hybrids. Dwarf Korean lilac cultivars are also available.
Preston lilacs (S. x prestoniae) bloom late in the lilac season, with loose, spicy scented flowers, large leaves, and an open growing habit. The Preston lilacs grow exceedingly fast, according to the North Dakota State University Extension, and can read 25 feet high, though they withstand frequent pruning. The Iowa State Extension advises that Preston lilacs are more resistant to downy mildew than are the common French hybrid lilacs. Since their blossoms follow the earlier French hybrids, they can extend the effect of lilac flowers in the landscape for several additional weeks. Several cultivars have pink flowers, easing the transition from the purples of lilac to the multi-colored flowers of the summer garden.