How to Grow and Care for Lilac Bushes

lilacs

The Spruce / Evgeniya Vlasova

Common lilac bushes (Syringa vulgaris) are deciduous shrubs that bloom in the springtime. They are part of the olive family, along with other such ornamental plants as ash trees, forsythia bushes, and privet shrubs. The outstanding quality of many lilac varieties is the sweet fragrances of their flowers. The blooms appear in branching clusters, or panicles. Each flower is only about 1/3 inch across. The leaves are gray-green to blue-green in color and reach around 2 to 5 inches long; they do not change color in the fall. And the bark of this shrub is gray to grayish brown. The best time to plant lilac bushes is in the early fall before the ground freezes. They have a moderate growth rate of 1 to 2 feet per year.

Common Name Lilac bush, common lilac
Botanical Name Syringa vulgaris
Family Oleaceae
Plant Type Shrub
Mature Size 8–15 ft. tall, 6–12 ft. wide
Sun Exposure Full
Soil Type Loamy, well-drained
Soil pH Neutral
Bloom Time Spring
Flower Colors Purple, white
Hardiness Zones 3–7, USA
Native Area Europe
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Lilac Care

Common lilac bushes are attractive enough to be treated as specimen plants, grown as focal points in the landscape. They are also often planted in rows along property borders and pruned into loose hedges. The 'Miss Kim' cultivar is small enough for use in foundation plantings, as is the even more compact 'Bloomerang' lilac, which is a dwarf shrub.

Once they’re established, lilacs don’t require much maintenance. They will typically only need watering during prolonged periods of drought, and they prefer annual fertilization. Pruning also is generally an annual task. 

lilac bushes

The Spruce / Evgeniya Vlasova

Syringa vulgaris 'Decaisne', Lilac with Juniperus x pfitzeriana 'Aurea' and Wisteria floribunda 'Macrobotrys', photographed in May at Wickham Place Farm, Witham, Essex, UK
Pedro Silmon/ArcaidImages / Getty Images
closeup of lilacs

The Spruce / Evgeniya Vlasova

lilac bush

The Spruce / Evgeniya Vlasova

Light

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.

Soil

Lilac bushes prefer a rich, loamy soil with sharp drainage and a neutral soil pH. They can tolerate clay soil, though it might stunt their growth.

Water

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.

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.

Fertilizer

Lilac bushes can benefit from a 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.

Types of Lilac

There are several types of lilac bushes that vary somewhat in appearance, including:

  • 'Wedgewood Blue': This compact lilac variety attains a height at maturity of only 6 feet with a spread equal to that. The flowers are contained in thick clusters of lavender blue. It thrives in zones 3 through 8.
  • 'Yankee Doodle': A small lilac bush with deep purple, fragrant blooms, Yankee Doodle is a bit more cold-hardy than the main species, suitable for zones 2 through 8. It grows 6 to 10 feet tall and 5 to 6 feet wide.
  • 'Belle de Nancy': This variety has double pink flowers (multiple layers of petals) and grows 8 to 10 feet tall and 6 to 8 feet wide. It blooms in late spring to early summer and is suitable for zones 3 through 9.
  • 'Madame Lemoine': Blooming with bright white double flowers, this lilac variety stands tall at up to 15 feet high and 12 feet wide. It is suitable for zones 3 through 8.
  • 'Primrose': Primrose is a standard-size lilac that grows 10 to 15 feet tall and 6 to 10 feet wide. It is notable for its yellow flowers that still deliver the beloved sweet lilac fragrance. It is suitable for zones 3 through 7.

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.

Propagating Lilacs

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.

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 combatting 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.

How to Get Lilacs to Bloom

Lilacs generally bloom in the mid- to late spring, though the exact timing can differ based on the variety. The conical clusters of tiny four-lobed flowers have an exceptionally sweet fragrance. The blooms only last for a couple weeks, but they should readily rebloom each year on a healthy plant. Deadheading, or removing the spent blooms, isn't necessary. To enjoy a longer blooming period, consider planting multiple lilac varieties that flower at different times.

A lack of sunlight is often the reason for poor flowering on a lilac. Watch your lilac for a full day to make sure it isn’t in the shade for any prolonged stretch. Lightly moist soil also encourages a stronger bloom. Mulch around the shrub can help to retain soil moisture and suppress weeds that might compete with the lilac.

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.

FAQ
  • Are lilacs easy to care for?

    Established lilacs are generally easy to maintain. They typically require annual pruning and fertilization, along with watering during periods of drought.

  • How fast do lilacs grow?

    Lilacs have a moderate growth rate, gaining on average 1 to 2 feet each year.

  • What's the difference between a lilac bush and a lilac tree?

    A lilac bush and tree are the same thing. The plant also goes by lilac shrub.