Selection and Growing Syringa or Lilac
Beautiful and Fragrant Spring-flowering Shrubs
Syringa (Syrin'ga). Leaf-losing shrubs or small trees, most of which are perfectly hardy in the North. They are distinguished by their opposite, often heart-shaped leaves, and by their large clusters of lilac, blue, reddish, white or cream flowers, which in some kinds are very fragrant.
The commoner kinds of Lilac are among the most popular of flowering shrubs, and the appearance of the flowers heralds the change of the season from spring to summer. They are wild in southeastern Europe and Asia, and upwards of twenty species are known, in addition to hundreds of hybrids and named varieties.
The word Syringa is sometimes used as a common name for the Mock Oranges or Philadelphus, but its correct use as a botanical name is for Lilac. Syringa belongs to the Olive family, Oleaceae, and the name is from the Greek, syrinx, a tube, possibly because the name was first applied to Philadelphus.
The wood of Lilacs is hard, close-grained, yellowish with brown and reddish marks. It is attractive and suitable for turnery, though rarely used for the purpose.
Lilacs lend themselves to many forms of garden decoration; very charming results are often obtained when they are planted at the foot of an old wall so that the flowering branches appear well above the top. They are also excellent for large and small groups, isolated specimens, masses in the shrubbery and for informal hedges. They are exceedingly popular with almost everybody, and few gardens of any size in temperate climates are without one or more.
Propagation by Seeds and Cuttings. The species or wild types can be increased by means of seeds sown in light soil in greenhouse or frame, as soon as ripe or the following spring. Cuttings of the leafy shoots of many varieties that cannot be grown true from seed, may be made 3-4 in. long in June and inserted in sand in a cold frame. Or cuttings 9 in. long may be made of ripened wood in late autumn and winter and buried in sand in a cold frame over winter, to be planted in nursery rows in the garden in spring. But all the named varieties are more satisfactory if raised from layers.
Layering. When only a few plants are required, it is enough to layer the lower branches, but when large numbers are wanted it is better to keep plants in a nursery bed purposely for providing layers. Some people graft named varieties on stocks of the common Lilac, Syringa vulgaris, but it is not a good practice, for S. vulgaris is so liable to produce suckers; if these are not pulled up, they will in time take over and smother the named variety. Privet has also been used as a stock for Lilacs, but it has not proved very satisfactory.
Hints on Cultivation. Loamy soil is best for Lilacs, although they thrive in light and in clayey land. Good results over a long period can only be expected where the soil is of good quality. If the soil is poor, growth becomes thin and weak, and flowering suffers. Lilacs are not difficult to transplant and the work can be carried out at any time in fall or spring. A surface dressing of decayed manure or rich compost placed above the roots every second year is beneficial, and several applications of liquid fertilizer applied during May and early June will materially assist growth.
Pruning should take the form of the removal of suckers from the base, and of weak shoots, especially those inside or towards the center of the tree. This should be done as soon as the flowers have faded, and the old flower heads should be cut off at the same time. Severe annual pruning, other than the removal of suckers, is not advised. But when the plants are becoming weak and few flower heads are formed, the removal of weak inside wood, supplemented by applications of fertilizer, often results in vigorous growth and more flowers. This is the case with the garden varieties rather than the species or wild kinds. A little occasional thinning is usually all that the latter require. Overgrown bushes may be pruned back into old wood, with the result that new shoots will be formed from dormant buds. In extreme cases, when the bushes have become excessively tall and leggy they may be cut down in early spring to within about 1 ft. of the ground. Following this severe operation they should be fertilized and kept well watered in dry weather. Under this treatment they will form shapely bushes and may be expected to begin blooming in 2-3 years.
Lilacs for Forcing. Lilacs for forcing in the greenhouse are often grown specially for the purpose and are usually restricted to a few branches. Weak shoots are removed in order that the full vigor of the plants can be concentrated on the production of a few strong growths with well-developed buds. During the growing season they are fertilized liberally, and about August each plant is chopped around with a spade, and the ground opened a little to check growth and assist in ripening the wood.
Forcing begins soon after the leaves have fallen, and the forced plants, after the flowers have been gathered, are cut back, hardened off and replanted out of doors to be forced again in about two years time.
The Common Lilac. S. vulgaris, is a large shrub or small tree sometimes 20 ft. high, with a trunk 9-12 in. in diameter. It is a native of southeastern Europe and has been grown in European gardens since the latter part of the sixteenth century and in American gardens since early colonial times. References are made to it in both the diaries of George Washington and of Thomas Jefferson.
The most attractive of the old, original forms or varieties bear large, dense clusters of very fragrant flowers. There are several varieties, including alba, with white flowers; caerulea, with rather slender clusters of small pale blue-lilac flowers; and purpurea, which is reddish-purple. But the typical kind and its early varieties have been superseded by the newer named varieties having superior forms and richer coloring. Because the early hybridization was carried out by the great French horticulturists the Lemoines (father and son) of Nancy, these hybrids are often called "French Lilacs." American hybridizers have raised a few varieties but even today the majority of the improved varieties of the Common Lilac, S. vulgaris, in cultivation were raised by the Lemoines.
More recently S. vulgaris has been hybridized with varieties of S. oblata. These are described below under S. oblata in the discussion of Chinese Lilacs.
Best Varieties of Common Lilac
Single-flowered:Vestale, white; Mont Blanc, white; De Mirabel, violet; Cacour, violet; President Lincoln, blue; Decaisne, blue; Maurice Barres, blue; Firmament, blue; Jacques Callot, lilac; Lucie Baltet, pink; Congo, reddish-purple; Mme. F. Morel, reddish-purple; Reaumur, reddish-pur‑ple; Ludwig Spaeth, deep purple; Monge, deep purple; Mrs. W. E. Marshall, deep purple.
Double-flowered: Ellen Willmott, white; Edith Cavell, white; Mme. Lemoine, white; Marechal Lannes, violet; Violetta, violet; Olivier de Serres, blue; President Grevy, blue; Victor Lemoine, lilac; Leon Gambetta, lilac; Henri Martin, lilac; Katherine Havemeyer, pink; Mme. A. Buchner, pink; Paul Thirion, reddish-purple; Mrs. Edward Harding, reddish-purple; Adelaide Dunbar, deep purple; Paul Hariot, deep purple.
The Hungarian Lilac. S. Josikaea, the Hungarian Lilac, forms a bushy shrub 10-12 ft. tall and bears slender clusters of slightly fragrant, deep lilac to violet-colored flowers in June. It is not particularly handsome in bloom; its chief value lies in the lateness of its flowering period. The variety of S. Josikaea named eximia has large clusters of rose-colored flowers. S. Josikaea has been hybridized in Canada with S. reflexa to produce the Josiflexa hybrids.
The Persian Lilac. S. persica, the Persian Lilac, is a singularly beautiful shrub when in flower. Forming a shapely bush of slender branches, it usually grows 4-5 ft. high, bears large numbers of small, graceful clusters of lilac-colored, sweetly scented flowers. It requires little or no pruning and always blooms well. The variety alba has white flowers, and in laciniata the margins of the leaves are divided into fine segments. Some botanists regard the variety laciniata to be a distinct species and name it S. laciniata, and believe S. persica to be of hybrid origin. S. persica is widely distributed from Iran to western China and has been known in European gardens since 1640.
S. persica, crossed with S. vulgaris, produced a very beautiful fragrant-flowered Lilac called S. chinensis. It is intermediate in habit between the two parents, forms a shapely bush 8-12 ft. high, and bears its clusters of fragrant, purplish-lilac flowers freely. The variety alba has white flowers. The variety duplex has double purplish-lilac flowers. S. chinensis is sometimes called the Rouen Lilac.
The Himalayan Lilac. S. emodi, the Himalayan Lilac, is another vigorous and attractive shrub; unfortunately it is not hardy far north. It may grow 15-18 ft. high, has large leaves, which are green above and silvery beneath, and bears dense heads of whitish-pink or lilac-tinged flowers in June and July that have a privet-like odor. It has been grown in gardens since 1840.
There is a variety, aureo-variegata, with golden-variegated leaves, and another, aurea, with yellowish leaves. S. hybrida is a hybrid between S. emodi and S. vulgaris, with characteristics most like those of the former.
Chinese Lilacs. S. pekinensis is a shrub or small tree of the same type; it has smaller leaves but very similar heads of flowers: its variety, pendula, is a very graceful shrub with drooping branches. It is a native of China.
S. Julianae is one of the best of the newer Chinese kinds. It was received from western China in 1900 and is a graceful, early-flowering bush 5-6 ft. high. The lilac-purple, fragrant flowers are in medium-sized clusters and open in early spring. There is a variety with white flowers. S. velutina (Palibiniana) is a vigorous bush, up to 10 ft. high, which was introduced from Korea in 1917; it bears long, slender branched clusters of pale lilac flowers. This kind is found wild in China and Korea.
One of the most conspicuous of the native Chinese Lilacs is S. reflexa, a vigorous shrub 10‑12 ft. high, from central China, with large
handsome leaves, and dense, nodding clusters of reddish flowers which open about the end of May. The leaves are often 5-51/2 in. long and 2-2 1/2 in. wide. Crossed with S. villosa it has become the parent of the very fine group of Canadian-raised hybrid Lilacs that are collectively called Prestoniae hybrids. Among the best of these varieties are Isabella, Jessica and Nerissa.
Hybridized with S. Josikaea, S. reflexa has given rise to a group of Lilacs called Josiflexa hybrids. These also were raised in Canada.
S. villosa is a large bush, 10-12 ft. high, native to northern China, and belonging to the same group as S. emodi. It flowers from short shoots produced on the previous year's wood, and on the tips of vigorous shoots of the current year, the latter bearing the finer clusters. The flowering time extends from the end of May to July. The flowers are usually rosy-lilac and freely produced. Owing to its vigorous and shapely habit and prolonged flowering, it is a shrub that deserves more attention from gardeners.
S. Komarowii is a large shrub, 16 ft. high, native to western China and closely related to S. reflexa; the flowers are reddish-purple and produced in dense nodding clusters in June.
S. microphylla is a graceful bush of slender growth with small leaves, scarcely more than an inch long, and branched clusters 4-5 in. long of small, tubular, lilac-colored flowers in June. It is a native of northern China.
S. pinnatifolia differs from the other Lilac species by bearing pinnate leaves, a characteristic only found elsewhere among Lilacs in the laciniate-leaved variety of S. persica. S. pinnatifolia is a native of western China, where it forms an erect bush about 10 ft. high. Its leaves are 1 1/2-3 in. long and are made up of seven to eleven small leaflets. The flowers are white, or white tinged with lilac, and are in small clusters up to 31/2 in. long. The plant is more curious than beautiful and must be regarded as one of the least decorative kinds.
S. oblata, from China, has the distinction of being one of the earliest of Lilacs to flower. It grows to a height of 12 ft. or thereabouts, and bears dense clusters of pale lilac-colored blooms in late April or early May. S. oblata variety alba has white flowers. Hybridized with the Common Lilac, S. vulgaris, S. oblata variety Giraldii has given rise to early-flowering hybrids which bloom a week or ten days before the Common Lilac. The best of these are Lamar-tine, pinkish-lilac; Louvois, dark lilac; and Montesquieu, dark lilac. S. oblata variety dilatata, hybridized with the Common Lilac, S. vulgaris, has given rise to the excellent hybrids Assessippi, lilac, and Pocahontas, purple, which bloom about ten days earlier than the Common Lilac.
S. Sweginzowii, a native of northern China, is an upright-growing shrub that attains a maximum height of about 10 ft. It has fragrant, lilac or reddish lilac-colored flowers in June. Its chief value rests in the lateness of its season of bloom. S. Sweginzowii variety superba is said to bloom more profusely but otherwise is similar.
S. tomentella (Adamiana), a vigorous bush from western China, has flower clusters rather like those of S. emodi, produced in June.
S. amurensis, from Manchuria and China, is a late-flowering kind that grows about 12 ft. tall and has creamy white flowers somewhat resembling those of a large-flowered Privet (Ligus trum).
The Japanese Lilac. S. amurensis variety japonica, the Japanese Lilac, is especially worthy of note; it is a small tree up to 30 ft. high and is remarkable for its huge bunches of small white or pale cream-colored flowers which open in June and July. At first sight they look more like flowers of giant-flowered Privet than Lilac. This kind is a native of Japan.