That Heady Scent of Spring: Lilacs
- Mikl Brawner
- Apr 1
- 7 min read
By Mikl Brawner:
Lilacs were brought to America by the earliest settlers and have been popular landscape shrubs ever since for good reasons. Tough, drought tolerant, usually healthy and long-lived, they have masses of beautiful flowers and most have a delicious fragrance. Even in dry Colorado air lilacs carry their rich perfume for quite a distance. Like most young boys, I was more interested in bugs than flowers, but my earliest memory of a flower was lying on a grassy hill next to a lilac hedge in full bloom, soothing my spring fever in the sweet, heady fragrance of the common lilac. This powerful aroma is one of their main attractions and the main reason why people forgive some other qualities, like their huge size and habit of suckering.
In fact, the tendency to sucker and the ease of transplanting are primary reasons for the rapid spread of lilacs across America. By the 1650s, lilacs were growing all over the colonies and later carried west by the pioneers. I recently pruned some lilacs that were planted by miners in the rocky foothills above Boulder. I can just imagine some rough traveler, burning with gold fever and the Colorado sun, sharing his canteen with a lilac sucker.
Lilacs are natives of colder regions of southeastern Europe and northern regions of China and Korea. What we call Common Lilac, Syringa vulgaris, came from Romania, Yugoslavia, and Bulgaria. The long-blooming species comes in purple and white, and is one of the most fragrant. It will grow to 12’-15’ and can spread to make wide clumps for a good screen. Native to limestone areas, they prosper in our alkaline soils. Their hardiness makes them endure in Colorado: books say Zone 4 but local growers say Zone 3 or even 2, and to 10,000’.
Lilacs have been hybridized so much that there are many colors and forms to choose from. At least 1500 cultivars were bred from Syringa vulgaris.
Starting in the 1880s, Victor Lemoine of France began selecting and hybridizing lilacs. It was a family enterprise with Victor as the leader, Madame Lemoine climbing ladders to do the actual cross pollinating, and their son Emile taking over the business. They achieved 214 successful varieties, what we now call the French Lilacs, and both Victor and Madame Lemoine have great lilacs named after them. Since Lemoine, there have been many lilac breeders, several from the United States, including Father John Fiala who wrote the great reference, Lilacs: The Genus Syringa.
Some successful Syringa vulgaris cultivars available in our area are:
‘Albert Holden’ - deep violet blossoms with a silver reverse, good fragrance, grows to 7’-8’.
‘Arch McKean’ -magenta flowers, very little suckering, to 7’-8’
‘Beauty of Moscow’ (‘Krasavitsa Moskvy’) - double white fragrant blossoms, to 10’-12’, (“one of the finest lilacs in commerce.” Fiala)
‘President Grevy’ - excellent double blue flowers in immense panicles
‘Edith Cavell’ - rated “excellent”, double white, very showy flowers
‘Monge’ - single deep purple, “outstandingly showy”, to 10’-12’. This one is thriving at the neglected Cheyenne Station in Wyoming.
‘Sensation’ – very striking, purple flowers edged with white (see below)
‘Marie Frances’ – true, soft pink, very fragrant flowers
Besides Syringa vulgaris there are 22 other species, all from Asia. Some are not garden worthy, but several were used in breeding great new hybrids and some make good shrubs in themselves. The beautiful Syringa laciniata is sometimes available. It is quite beautiful with cut leaves and lavender blossoms. It is long-flowering and suckers very little.
Syringa meyeri is compact and the variety ‘Palabin’ is available locally. It grows to 5’, needs little pruning and likes loose soils. It has deep purple buds, lavender-blue flowers, and succeeds in dry conditions.
Syringa microphylla ‘Superba’ has small leaves as its name implies. Slow growing to 6’-8’ and wide spreading with small clusters of dark pink flowers that are sweetly fragrant it will make a few blooms again in summer and fall.
Syringa oblata is occasionally available and although it is an early bloomer, it is less susceptible to freezing than S. vulgaris and so is fairly reliable. The flowers are pale purple and fall leaf color is wine red. The variety dilatata is a superior form with very fragrant purple flowers and the variety ‘Cheyenne’ is extremely fragrant.
Syringa x hyacinthiflora is a cross between Syringa oblata and S. vulgaris. They bloom 7-10 days before the French Vulgaris hybrids. The fragrant flowers can be white, lavender or purple, fall color is wine red. These are successful, large, dense shrubs for Colorado, growing to 10’-12’, and can be used as hedges since their leaves and flowers form all the way to the lower branches. Though hardy to 9000’, they bloom early, so avoid planting in a frost pocket or next to a wall or house where the flowers may open early only to be frozen. A few available locally are ‘Mount Baker’ with very fragrant, pure white flowers, ‘Assissippi’ which is the earliest with fragrant lavender flowers, and ‘Pocahontas’ with deep violet fragrant flowers.
Syringa patula is a late blooming species from the mountains of South Korea. The selection ‘Miss Kim’ has a fabulous compact form and very fragrant ice-blue-lavender flowers. It has burgundy fall color and prefers a well-drained soil.
Syringa x prestoniae are a series of hybrids from crossing Syringa villosa and S. reflexa. Isabella Preston was the Canadian hybridizer of these prolific bloomers. They flower 10-14 days later than S. vulgaris and have a spicy “oriental” fragrance. Very hardy to Zone 2 and to 9000’ or 10,000’, they do not sucker and can be pruned into small multi-stemmed trees. Some varieties available locally are: ‘Isabella’ with lavender flowers, ‘James Macfarlane’ with pink flowers, ‘Miss Canada’ with deep pink flowers and ‘Minuet’ with purple flowers, both growing to 6’-9’.
Another species favorite in Colorado is Syringa reticulata, the Japanese Tree Lilac. It grows to 15-25’, blooming with white flowers in very late spring. The variety ‘Ivory Silk’ has a more compact form and the same cinnamon-brown peeling bark. The fragrance is like privet, that is, not delicious. It is hardy to Zone 4 and 6500’.
The best culture for lilacs is fertile, well-drained soil with plenty of organic matter in full sun. The Common Purple and Common White seem to do just fine in my lean gravelly soil with almost no organic matter, but for the hybrids, higher fertility is necessary for longer bloom, bigger and more flowers. Father Fiala says commercial fertilizer is no substitute for two-year-old manure and compost, because they provide tilth, hold moisture and feed the soil microorganisms. The worst conditions for lilacs are “wet feet”, shade and subsoil. If heavy wet clay is all there is, Father Fiala says to build a 3’ high mound with gravel, top soil, manure and compost; and plant at the top of the mound. Another option is to plant near the top of a slope; never near the bottom. Syringa vulgaris and its offspring are the most tolerant lilacs for heavy clay, but not if it is soggy.
The best pruning for lilacs is to remove the dead, broken and very old. Also take out many of the suckers, but leave the biggest ones if they aren’t too crowded. Once the shrub is mature, remove a fourth to a third of the oldest wood every year. Prune the tallest branches down 10%-20% to a side branch leading out. This should be done soon after blooming so next year’s buds are not removed.
When a lilac has not been blooming well or has gotten very old with little care, it can often be rejuvenated if the roots are sound. First scratch in some composted manure into the top 2” of the soil, then mulch 3” deep. Cut out the oldest canes, or if it has too much dead, cut the whole shrub to the ground in the early spring before it leafs out. This will either renew it or, if the roots are rotten, it may not survive the operation. Do not cut a weak lilac to the ground in the summer, because that would likely kill it.
There is not universal agreement as to the value of dead-heading the spent flowers, but Father Fiala and the Arnold Arboretum believe it is worth the trouble if done immediately after blooming. This will save energy resulting in better blooming and health. It can be a big job, but I have found removing even half the spent flowers is helpful.
Lilacs are generally healthy if they get decent drainage, some pruning, and some organic matter. But they can have a few problems. In Colorado, a warm February and March followed by a frigid April or May can freeze the buds or flowers and ruin the floral show for a whole year. Another problem can be powdery mildew, turning the leaves almost white. If the plant is strong, this will cause no real harm; just rake up the diseased leaves. Some varieties like Syringa meyeri, S. microphylla, S. reticulata, ‘Mme. Lemoine’ and ‘Pocahontas’ are resistant to mildew. You can control the mildew with a non-toxic spray of horticultural oil and baking soda, one tablespoon each in a gallon of water, or a product related to baking soda called Green Cure. One other possible problem is lilac borer which can tunnel into the wood to weaken or kill stems. This should not be a problem if the plant has good vitality. I have heard “painting” the lower trunks with wood ash and water repels them.
Like every plant, lilac has strengths and weaknesses, but far more strengths. It is truly a sustainable shrub for Colorado, being tough, drought tolerant and fire retardant. Enjoy the great variety of forms, flower colors and fragrances. By planting the early, middle and late bloomers, you can enjoy a long season of flowers. I recommend that you go to the nurseries in the spring when they are in bloom so you can smell, see, and cultivate those that really speak to you.
Mikl Brawner owns Harlequins Gardens Sustainable Nursery in north Boulder with his wife Eve.
