April 2001 

Did you know that Syringa genus has good and bad bloom years?

We Homo sapiens are fond of referring to our bad hair days, and the equivalent in the Syringa genus is the bad bloom year. These shrubs, much treasured for their fragrant flowers, are notorious for underperforming after winters that don’t offer the degree of cold they require. But when they have a good year, as this one seems to be, few plants rival the sensational combination of floral brilliance and powerful fragrance of the common lilac. All over town this spring, the lilacs are outdoing themselves. Enjoy them while they last, and take a few steps now to boost the overall condition of your shrubs so that maybe, just maybe, they’ll reward us with another show-stopping performance next year.

The name of this genus is from the same root as syringe, derived from the Greek word for “pipe.” In case you’ve ever wondered which came first, the naming of the color or of the plant, we can at least solve that mystery: the plant acquired the common name, lilac, because of its purple flowers. Lilac can be traced to the Sanskrit word for purple. 

There are hundreds of named varieties of Syringa vulgaris, as well as several other species of Syringa to choose from. Most are staples of the shrub border, traditionally placed at the back. Many of the S. vulgaris varieties are collectively known as the French hybrids, because they were developed by devotees at gardens in Rouen and Nancy in the late 19th and early 20th centuries. The named varieties and several species offer different forms, ranging from arching to upright; variations in flower color from pure white through pale yellow to deep purple (some with a tendency to fade); different intensity of fragrance; and choices in flowering time, from early to late spring.  Whatever the variety, you should provide it with full sun, the opportunity for it to spread its branches and still have plenty of air circulation, and well-drained soil that is not acidic. Lilacs appreciate an alkaline soil; and many sources recommend adding lime out to the drip line in the fall. Feed your lilac twice a year, once in late winter or very early spring, and again after bloom.

Pinch back your young lilac to establish its shape, and remove old blossoms as promptly as you can. Remember that next year’s flower buds form in pairs where the leaves join the stems; severe pruning will mean fewer blossoms in the following year. As with other flowering shrubs, pruning is best done right after flowering, to preserve as many of next year’s flowers as possible. If you need to completely renovate an older lilac, do the severe cutting back during the winter, while the plant is fully dormant. Suckers are often a problem, particularly if you’ve purchased a lilac that’s grafted onto root stock. Watch out for leaf miners, leaf spot, lilac blight, and powdery mildew, and treat as indicated in your Master Gardener materials. These problems will be less severe if you take proper care of your lilac right from the beginning of your relationship with it. They are tough plants, these lilacs, and they will provide you with beauty most every spring for many years, in return for regular, routine care from you.

source:
http://whatcom.wsu.edu/ag/homehort/plant/lilac.htm
http://www.canr.uconn.edu/plsci/mbrand/s/syrvul/syrvul1.html