Published in Escarpment Views, Summer 2008:
     Lilacs bloom a short two weeks in late May or early June. Are they worth the trouble?
     If you like burying your face in masses of stunning colours and inhaling rich scents down to the bottom of your lungs, they are. If you enjoy filling your rooms with vases full of lush branches of flowers, they are.
     Lilacs have been so beloved for centuries that early settlers in Canada brought them from Europe to plant near their new homes. Some remain today as signs of vanished homesteads and ghost towns. Lilacs are native to Asia and Europe, so they appeal to people from many cultures.
     “From childhood, people are used to seeing them,” says Alex Henderson, curator of collections and horticulturist for the Royal Botanical Gardens (RBG) in Burlington. “They were one of the first plants I became aware of. They took my imagination as a child.”
     Henderson originates from England, where he trained as a horticulturist and worked at some private gardens and at Kew Gardens. For the last 18 months or so he has worked at RBG, which has the distinction of being the largest botanical garden in the world.
     Henderson explains that there are 21 distinct species of lilacs. Only two of them are native to eastern Europe. The other 19 come from Asia. In 1563 the first Asian lilacs came to Austria as a gift from the ruler of Constantinople.
     One of the European kinds, Syringa vulgaris, was used by Victor Lemoine of France in the 1800s to create hybrids. Lemoine’s many French hybrids are still popular today. Later, a Canadian, Isabella Preston, was successful in developing large, late-blooming, extremely hardy hybrids. These Preston hybrids can even grow in Thunder Bay.
Care of Lilacs
     For Henderson’s four main rules for caring for lilacs, see the sidebar. He explains that lilacs don’t like being waterlogged, that they need good light and should be irrigated in July and August when next year’s buds are being formed.
     Deadheading should be done to prevent seed production right after blooming. Dead flowers should not be ripped off, but snipped below the spent flowers.
     Proper pruning leads to better flowers and leaves. Remove dead or injured material as well as any branches that are crossing and could lead to wounds from rubbing. Good lilac bushes have seven to 12 stems that are six to nine feet high so that the blooms are at head height.
     For the best blooms, he recommends branches of different thicknesses from three to eight cm in diameter. With branches larger than 10 cm in diameter, however, flower production decreases. These branches should be cut right to the ground. Henderson assures that suckers are good as they will eventually form new branches. He also suggests forking the roots slightly to stimulate growth.
     “Treat them mean, keep them keen,” he says with a grin.
Rejuvenation Pruning
     If lilacs have grown out of control, they can be rejuvenated. For three years, prune back one third of the growth right down to the ground. That way, in three years there will be new growth, intermediate growth and older growth. From the third year, regular pruning can be done to keep the bushes in good shape.
Feeding
     Henderson advises cutting a mulch circle around the drip line to keep weeds down and moisture in. Every spring, add fertilizer that’s high in phosphate, to promote flower production. Every third year, it’s good to sprinkle ground limestone around the drip line.
Propagation
     Within two weeks of flowering, it’s all right to transplant suckers. Another technique is to take softwood cuttings off the main plant in the early morning. Dip the end in rooting hormone, plant the cutting in clean soil and cover it with plastic to keep it moist. When roots form, repot in bigger pots. This method can take four years before there will be blooms. A third way is grafting, but Henderson admits this is not for most amateur gardeners.
Lilacs in the Dell
     RBG has one of the largest lilac collections in the world and is the International Registration Authority for new lilac cultivars. There are more than 1,600 cultivated varieties of lilacs. RBG has approximately 633 kinds.
     “All our plants are like library books,” Henderson says. “Each one is numbered and documented.”
     An overwhelming number can be seen in bloom at the RBG’s Lilac Walk and Lilac Dell. The dell was begun in the 1960s when Katie Osborne provided a generous donation to increase the number of lilacs. Henderson sees the collection as having great cultural value to the people of Ontario and all of Canada. There is a problem, however.
     “A lack of recent funding has led to the irrigation system not functioning well,” he says. “It’s old and needs replacing. For this, we need sponsorship or donations.”
     RBG hosts an annual lilac festival when the blooms are at their peak. When the weather cooperates, people flock to them in great numbers. Henderson is often stopped to answer questions or take photos of people. He obliges with great patience, seeming to enjoy their pleasure in the gardens.
     Visitors approach the dell by way of the Lilac Walk which is planted as a teaching garden going from the original species of lilacs to some of the many hybrids. There are many cries of “Ooh” and “Ah” and “Smell this!” as people explore the blossoms.
     In the dell that slopes down a hillside, people with cameras are everywhere, unless they’re sitting on benches or the ground, simply relaxing and feeling transformed by the beauty. Henderson explains that the slope of the dell gives various experiences of scent. In the evening when the cool air sinks, the bottom of the dell captures all the fragrance.
     One close-up inhalation of a scented lilac is worth all the care.
     For information about other garden events this summer at RBG, see www.rbg.ca or call 905 527 1158.
[Sidebar 1]
Colour Categories of Cultivated Lilacs
1. white
2. violet
3. bluish
4. lilac
5. pink
6. magenta
7. purple
[end of Sidebar]
[Sidebar 2:]
Extend the Blooms
Henderson recommends planting three different kinds of lilacs that bloom at different times, to get a long blooming season of six to seven weeks:
1. Hyacinthiflora (first to bloom)
2. French hybrids (mid season)
3. Prestons (late flowering)
[end of Sidebar]
[Sidebar 3:]
Caring for Lilacs:
1. Plant in soil with good drainage.
2. Provide at least four hours of sunlight a day.
3. Water well in July and August.
4. Prune and deadhead.
[end of sidebar]