Luscious Lilacs

By David Tarrant | Image: John Glover

Like many gardeners, whenever I think of lilacs, my mind is immediately flooded with fond memories of warm late spring days when the air around a lilac bush is heady with delicate perfume, and all seems well with the world.

This well-loved genus of deciduous small trees and shrubs, known botanically as Syringa, includes only about 20 species. However, because of its popularity as a garden must-have, much hybridization has been carried out by lilac enthusiasts over the years, resulting in a great number of named cultivars.

The true species are native across a wide range, which means considerable variation in the hardiness of different lilacs. Two lilacs originate from Europe, one in the Himalayas and the others range throughout eastern Asia as far south as Yunnan in China.

As for cultural requirements, lilacs prefer a good sunny exposure in well-drained but rich soil. At planting time add a healthy amount of compost to the hole and backfill the soil. In subsequent years add a mulch of compost to the root area about 7 cm (3 in.) deep when the new growth begins to break.

Lilacs also prefer their soil to be on the alkaline side. If you live in an area where the soil tends to be acidic, as it is out here on the coast, sprinkle a handful of dolomite lime per square metre or yard around each bush in the fall. Lilacs work well as single specimens in a lawn or courtyard, or they can be incorporated into the back of larger mixed borders with other shrubs or perennials.

The common or French lilac, Syringa vulgaris, is one of the best-known lilacs, and coming to us from the higher altitudes of eastern Europe, it is hardy in zones 4 to 8. Its multi-stem habit makes it a great candidate for a hedging screen. At maturity it can reach 7 m (23 ft.) in height. Its foliage is typical of the genus, ovate to heart-shaped, with opposite leaves growing to 10 cm (4 in.), and stems bearing highly scented lilac-coloured flowers that occur in dense conical panicles from late summer to early spring. This is truly the lilac that inspired the classic Ivor Novello song that goes, "We'll gather lilacs in the spring again . . ."

Syringa vulgaris has many wonderful cultivars. 'Primrose' is quite striking, with its heavenly scented flowers a pale primrose-yellow, the colour of cream. Another favourite is 'Charles Joly,' which has deep double purple flowers, but for pure-white beauty, look for 'Mme. Florent Stepman.'

Other beauties worth mentioning are 'Louis Van Houtte,' 'Sensation' (with wine-coloured blossoms edged in white), 'Angel White' and 'Andenken an Ludwig Späth' ('Souvenir de Louis Spaeth').

Similar to S. vulgaris and also often found in older gardens, Syringa x chinensis reaches a height of about 5 m (17 ft.) with abundant lilac-purple and very fragrant flowers. Good for zone 5 and up.

One thing that all true gardeners share is patience, and these lilacs, if purchased as small gallon-container plants, can often take five to seven years to flower. Those new to gardening may throw up their hands in horror when they hear this, but experienced gardeners know this is just part of the charm of gardening, and five years is but a flash in the grand scheme of things.

If you simply can't wait that long, you may want to purchase a mature plant in a larger container. Newly planted lilacs should be deadheaded before they have a chance to form seed. This will allow all the energy to go into the production of flowers for the following spring. Also, because this group is multi-stemmed, prune out any spindly stems as you remove the dead flowers. In fact, dead flowers should be removed every year as long as you can reach them.

The large group of hybrids that comprises Syringa x hyacinthiflora includes probably the hardiest of all lilacs, being suitable for zones 3 to 7. As the name suggests, most of these plants have much larger showy panicles, resembling the flowers of a hyacinth. Resulting from crossing the Korean species S. oblata with S. vulgaris, this lilac has an upright growth habit when young, but becomes more spreading with maturity. Its leaves are heart-shaped, 10 cm (4 in.) long and sometimes display a bronze hue during the plant's early years.

In this group, one notable cultivar is S. x hyacinthiflora 'Blue Hyacinth,' which has large, eye-catching, single lilac/blue flowers with a divine perfume. Equally noteworthy is S. x hyacinthiflora 'Cora Brandt,' with its large (23 cm/9 in.) panicles of double white flowers.

Another most attractive - and again reasonably hardy - lilac is Syringa sweginzowii. Native to southwest China, it is more of an upright shrub reaching four metres at maturity. Its leaves are ovate-lanceolate and somewhat thin in texture compared to other lilacs. Its blooms are rather loosely arranged in upright panicles and the individual flowers are somewhat tubular. It has good scent with flowers ranging in colour from pale pink to white. Being hardy in zones 6 to 7, it flowers late spring to early summer.