An old and often repeated saying is that lilacs should be chosen in the spring but planted in the fall. Like most sayings of this kind, it is sound but needs qualification.
Lilacs, like any other plant, behave differently in different environments. Some are dependable bloomers, others are rapid growers, and many are slowly blooming even though the bush itself grows fast.
Judging from my observation of over 50 varieties, some are more susceptible to scale attacks than others. This is a matter of considerable importance if you are concerned with the amount of spraying required to keep a bush healthy and flourishing.
Some varieties, even when fully grown, may have a fragrance that varies from year to year. The variety Night is a conspicuous example of this in our garden.
Adding Lilacs To Your Garden
If you are thinking of adding lilacs to your garden, you should consider several things.
One important aspect is floriferousness. Profuse bloom varies not only with soil and weather but also with individual specimens.
The general health of the shrub is important too. Certain varieties also tend to be biennial bloomers. The rating of these characteristics will vary from person to person but are important to the buyer.
Lilacs may remain scentless, or nearly so, for one or several years before acquiring their characteristic perfume. On the other hand, some are fragrant from the first and retain a lasting fragrance. It should be noted that lilacs differ in fragrance.
Among my lilacs, one has an intense, sweet fragrance, another an almost equally intense but only moderately sweet fragrance, and a third an intense but, to me at least, a somewhat offensive odor.
Most visitors to our gardens are attracted by the fragrance of the hairy lilac (Syringa pubescens), but some find it almost repellent.
Consider These Factors
Habit and rapidity of growth are other factors that prospective purchasers should consider.
Most white lilacs tend to grow quite tall unless held in check by pruning. Most of the Skinner hybrids from Canada demand plenty of room to be at their best.
Some, like Decaisne, though not slow growers in the proper sense of the word, never grow beyond 6′ to 8′ feet.
There is much to be said for keeping lilacs under 10′ feet’ for ease in pruning and spraying if they are not employed to screen out a road or some unattractive view.
Preventing Powdery Mildew
The health of a bush is also a major consideration. Contrary to the belief of many gardeners, species and varieties differ in susceptibility to mildew and to scale insects.
Minnehaha and De Miribel are frequently attacked by mildew, while Ludwig Spaeth and Montaigne often have scale.
Powdery mildew can be prevented from attacking lilacs, but once the mycelia have invaded the leaf, it is impossible to destroy the fungus. In the past, sulfur has been the best preventative, but it should not be used if the temperature is 80° degrees Fahrenheit or higher.
Karathane, a phenyl crotonate, is most often used now. Scale, especially oyster shell, is most important on lilacs but easily eradicated by a delayed dormant miscible oil spray. Instead, use a highly refined oil and delay the application until the buds begin to swell in the spring.
Visit parks and nurseries to see specimens in actual environmental conditions. This is an invaluable aid when making a final decision.
A study of Lilacs for America published in 1958 by the American Association of Botanical Gardens and Arboretums is in most libraries.
44659 by Sven Nilson