Lilacs are one of the most recognized and best loved shrubs found in Nebraska landscapes. It’s also one example of a plant that performs wonderfully in northern gardens, hardiness zones 3-7 for most species, but lacks vigor and does not flower reliably in southern gardens (Zone 8 and higher).
Lilacs are easy to grow and tolerate much abuse, particularly S. vularis. As with most blooming plants, lilacs prefer full sun locations and well drained soil. Plants in shady locations frequently struggle with powdery mildew fungus each year. Old flowers should be cut off as soon as flowers fade. Annual pruning helps to keep plants vigorous and blooming profusely.
Common species of lilacs include the following:
- Syringa meyer , Meyer Lilac (often called Dwarf Korean lilac) - a dense, neat lilac with a good uniform outline. Violet-purple flowers produced in May are softly fragrant. Literally covered in flowers when blooming. Height 4-7 feet, width 5-6 feet. ‘Palibin’ is a compact form that grows 4-5 feet high and 5-7 feet wide with reddish-purple flowerbuds that open to whitish-pink flowers.
- Syringa microphylla , Littleleaf Lilac- smaller leaves result in a finer textured shrub, when compared to S. vulgaris. A handsome, broad-spreading shrub grows 6 feet tall and 9-10 feet wide. Fragrant, rosy-lilac flowers. Works well in a shrub border, groups or as a hedge. ‘Superba’ had single, deep pink flowers and is quite floriferous.
- Syringa persica , Persian Lilac- a graceful shrub with upright, arching branches reaching 4-8 feet in height and 5-10 feet in width. Dark green foliage and pale lilac, fragrant flowers produced in May. A nice small lilac with a mass of flowers in season.
- Syringa reticulata, Japanese Tree Lilac- a large shrub or small tree form of lilac reaching a height of 15-20 feet, and width 15 feet. Stiff, spreading branches develop an oval to rounded crown. Creamy, white, fragrant flowers are produced in June. An excellent specimen tree and small enough to plant under utility lines. If allowed to develop into a tree, annual pruning is not necessary.
- Syringa villosa , Late Lilac- blooms in late May or early June, later than other lilacs. A bushy shrub of dense, rounded habit with stout, stiff upright branches. Many cultivars are available with flower colors including pink, dark purple-red, violet, rosy lilac and white. Not as fragrant as S. vulgaris. Height 6-7 feet, width 6-8 feet.
- Syringa vulgaris , Common Lilac- the most common form of lilac grown in Nebraska, forms an upright shrub with a height of 8-15 feet and width of 6-15 feet. Blooms in May with extremely fragrant flowers. Well over 400 cultivars are available including a wide range of colors and flower forms.
Lilacs should be pruned after blooming. Prune out one-third of the oldest, woodiest stems as close to the ground as possible each year. This encourages the plant to generate new stems each year, and avoids the development of thick, heavy stems that are attractive to borers.
Renewing Old Lilacs
Unfortunately, as lilacs mature, the lower portions of the shrub become shaded and usually lose their leaves. As a result, large, overgrown specimens are often leggy and unattractive. Their thick, heavy stems are very attractive to lilac borers. Old, neglected lilacs can be renewed or rejuvenated by pruning. Home gardeners can choose between two different pruning methods.
The best way to rejuvenate old lilacs is to cut back the overgrown shrubs over a three-year period. Begin the procedure by removing one third of the large, old stems at ground level in late winter. The following year, again in late winter, prune out one half of the remaining old stems. Finally, remove all of the remaining old wood in late winter of the third year. Additional thinning of the new shoots should also be done if the new growth is too dense. Since lilac wood needs to be 3 or more years of age before it blooms, this pruning method should allow you to enjoy flowers every spring.
One way to renew an overgrown lilac is to cut the entire plant back to within 6-8 inches of the ground in late winter, March or early April. This severe pruning will induce a large number of shoots to develop during the following growing season. In late winter of the next year, select among last year's new shoots and retain several strong, healthy shoots to form the shrub framework. Remove all other shoots at ground level. Cut back the retained shoots to just above a bud; this encourages branching.
When properly pruned, an old, overgrown lilac can be transformed into a vigorous attractive shrub within a few years. Once rejuvenated, pruning should be a regular part of the maintenance program for lilacs. The shrub can be kept healthy and vigorous by removing a few of the oldest branches every 3-5 years.
|
