Lilacs truly smell like spring! Lilacs are among the most carefree spring-flowering shrubs and provide a sweet, haunting fragrance, too! Learn how to plant, grow, and prune your lilacs. Lilacs, said to symbolize the joy of youth and associated with spring’s awakening, are hardy, easy to grow, and low-maintenance.
| Common name | Common Lilac, English Lilac, French Lilac |
| Botanical name | Syringa vulgaris |
| Family | Oleaceae |
| Species | vulgaris |
| Origin | Balkan Peninsula |
| Life cycle | Perennial |
| Plant type | Edible |
| Hardiness zone | 3, 4, 5, 6, 7 |
| Sunlight | Full Sun |
| Maintenance | Low |
| Soil condition | Clay |
| Soil ph | Alkaline |
| Drainage | Well-Drained |
| Growth rate | Medium |
| Spacing | 6 – ft. – 12 ft. |
| Flowering period | Spring |
| Height | 8 ft. – 16 ft. |
| Width | 8 ft. – 16 ft. |
| Flower color | Blue |
| Leaf color | Blue |
| Fruit color | Brown, Copper |
| Stem color | Brown, Copper |
| Fruit type | Capsule |
| Flower benefit | Edible |
| Garden style | Butterfly Garden |
| Uses | Patio |
I. Appearance and Characteristics
Syringa vulgaris, the lilac or common lilac, is a species of flowering plant in the olive family Oleaceae, native to the Balkan Peninsula, where it grows on rocky hills. Grown in spring for its scented flowers, this large shrub or small tree is widely cultivated and has been naturalized in parts of Europe, Asia and North America. It is not regarded as an aggressive species. It is found in the wild in widely scattered sites, usually in the vicinity of past or present human habitations.
Syringa vulgaris was first formally described by Carl Linnaeus in 1753 and the description was published in Species Plantarum. The Latin specific epithet vulgaris means “common” (in the sense of “widespread”).
Syringa vulgaris is a large deciduous shrub or multi-stemmed small tree, growing to 6–7 m (20–23 ft) high. It produces secondary shoots from the base or roots, with stem diameters up to 20 cm (8 in), which in the course of decades may produce a small clonal thicket. The bark is grey to grey-brown, smooth on young stems, longitudinally furrowed, and flaking on older stems. The leaves are simple, 4–12 cm (2–5 in) and 3–8 cm broad, light green to glaucous, oval to cordate, with pinnate leaf venation, a mucronate apex, and an entire margin. They are arranged in opposite pairs or occasionally in whorls of three.
The flowers have a tubular base to the corolla 6–10 mm long with an open four-lobed apex 5–8 mm across, usually lilac to mauve, occasionally white. They are arranged in dense, terminal panicles 8–18 cm (3–7 in) long. The fruit is a dry, smooth, brown capsule, 1–2 cm long, splitting in two to release the two-winged seeds.
II. How to Grow and Care
Sunlight
Grow lilac bushes in full sun, meaning at least six hours of direct sunlight on most days. Lilacs will tolerate some shade, but too little light can limit their bloom. They do not do well in full shade.
Temperature and Humidity
Lilacs bushes prefer climates that have fairly cool summers. They are not recommended for hot, humid areas, such as the Southern United States. High humidity can lead to fungal diseases on the plant. Moreover, lilacs can tolerate temperatures well below freezing, though they prefer protection from bitter cold winds, which can damage their flower buds and break stems.
Watering
Lilacs like a moderate amount of soil moisture. But soggy soil can lead to root rot and poor blooming. Water young lilacs regularly to keep the soil lightly moist. Mature plants typically will only need watering during periods of drought.
Soil
Lilac bushes prefer rich, loamy soil with sharp drainage and a neutral soil pH. They can tolerate clay soil, though it might stunt their growth.
Fertilizing
Lilac bushes can benefit from spring feeding, especially if you have poor soil. However, don’t use a fertilizer that’s high in nitrogen, which can lead to poor blooming. Instead, use a balanced fertilizer, following label instructions.
Planting Instructions
If you’re lucky, a friend will give you a sucker, or offshoot, of the root system of one of their plants. The sucker will look pathetic at first, but dig a hole, backfill it with soil, and stick the sucker in. Then, water and wait. In 4 or 5 years, you’ll be rewarded with huge, fragrant blossoms.
Transplanting nursery-bought lilacs is also easy. If it’s container-grown, spread out the roots as you settle the plant into the ground; if it’s balled or burlapped, gently remove the covering and any rope before planting. Set the plant 2 or 3 inches deeper than it grew in the nursery, and work topsoil in around the roots—water in. Then, fill in the hole with more topsoil.
Space multiple lilac bushes 5 to 15 feet apart, depending on the variety.
Pruning
Pruning is critical for lilacs, both to promote flowering and to ensure air circulation to prevent powdery mildew and other problems. The right time to prune is just after flowering is over, as lilacs bloom on old wood. Prune branches to thin out the growth (for better air circulation) and to keep the height of the shrub in check. Cut the oldest branches to the ground, as they won’t be strong flower producers anymore, but don’t take off more than a third of the total branches. Also, prune any weak or damaged branches.
Propagation
Anyone who has grown lilacs knows how readily they expand. Most lilacs are clump-forming plants that spread via shoots extending from the trunk. And these shoots can be used for propagation. Not only is this an inexpensive way to gain a new lilac bush, but it also prevents the existing lilac from becoming overcrowded. The best time to propagate is in the late spring to early summer to give the shoot enough time to become established before cold weather sets in.
To propagate, simply dig down around one of the shoots and cut it from the main plant, keeping the roots intact. Then, replant the shoot in rich soil wherever you wish, and keep its soil lightly moist (but not soggy) at all times until it’s established.
Pests and Diseases
Common Pests & Plant Diseases
Lilacs are fairly hardy shrubs and can survive most pest and disease problems. However, they are susceptible to several. The fungal disease powdery mildew is commonly seen on lilacs, especially during humid summers. It creates whitish powdery patches on the foliage. There are both chemical fungicides and natural methods for combating powdery mildew. The disease usually won’t be fatal, but you should still treat your lilac as soon as possible to limit fungal spread.
Common pests that can affect lilacs and damage their foliage include scales and borers. If you spot these tiny insects on the stems and undersides of leaves, treat your plant with neem oil or another insecticide.
Common Problems With Lilacs
Lilac shrubs are typically not problem plants in the garden. But they can encounter a few common issues.
Poor Flowering
A lilac that isn’t flowering as much as it used to might need a rejuvenation pruning. To do so, remove a third of the oldest branches right after the bloom period is over. In the next growing season, remove half of the remaining old branches after flowering. And in the next year, remove the rest of the remaining old branches. New branches that flower more vigorously will replace them in a few years.
Leaves Turning Brown
Lilac leaves turning brown might be due to several factors. Insufficient water, especially for young plants, can result in browning leaves. Too much fertilizer also can damage the foliage, as can prolonged exposure to very strong sunlight. Most often, though, brown spots on the leaves are due to bacterial blight. This infection typically occurs when growing conditions for the lilac are subpar. So correcting its conditions is one of the best remedies for the disease. Also, promptly remove infected foliage to prevent the disease from spreading.
III. Uses and Benefits
- Ornamental uses
The lilac is a very popular ornamental plant in gardens and parks, because of its attractive, sweet-smelling flowers, which appear in early summer just before many of the roses and other summer flowers come into bloom.
- Culinary uses
Lilac flowers are edible, but flavor varies among cultivars, from no flavor to “green” and lemony flavors. Gather insect- and disease-free blooms early in the day. Avoid any that are unopened or past their peak. Wash the flowers gently in cool water. Pat them dry and refrigerate until ready to use.
Consider making candied lilac flowers for a special cake decoration: Separate the individual flowers. Using tweezers, dip each one into a beaten egg white, reconstituted egg white powder, or packaged egg whites. Then, dip the flower in finely granulated sugar. Set it aside to dry before placing it on a cake.
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