Tips for Growing Common Lilac (Syringa Vulgaris) in Your Garden

The common lilac (Syringa vulgaris)—also known as the French lilac or simply the lilac—is a member of the olive (Oleaceae) family. Its relatives include ash trees, jasmine shrubs and vines, forsythia bushes, and privets. The common lilac is a popular ornamental landscaping plant that's fairly low-maintenance under the right conditions.

Native to the Balkan Peninsula, lilacs have long been revered for the heady scent of their abundant flower clusters. In the 1500s, the flowering shrub found its way to northern Europe, and settlers brought it to North America in the 1700s. New Hampshire even made the lilac its state flower.

Caring for the Common Lilac

Common lilacs are very low-maintenance plants and require little care beyond annual pruning and fertilization. They are great plants for landscaping, including border plants and hedges, and are quite beautiful on their own. Flowers from lilacs are fragrant and come in a multitude of colors.

Light

• Plant your lilac in an area that receives at least six hours of full sun each day.
• Lilacs will grow in some shade but likely won't produce as many of the prized blooms.

Soil

• Common lilacs like loamy, somewhat moist, neutral to slightly alkaline soil.
• Lilacs must have good drainage to avoid root rot and other diseases.
  

Water

• Lilacs can tolerate the occasional drought but likely would benefit from supplemental watering during excessively hot, dry stretches.

Temperature and Humidity

• The common lilac prefers USDA growing zones 3 through 7.
• Lilacs enjoy a moderate to cool temperature in the summers, up to 75 F, and can handle freezing temperatures during the winter.
• These plants thrive in moderate to less humid but do not tolerate high humidity.
• Lilacs do not tolerate areas such as the southern United States, as the temperature is too hot.

Fertilizer

• Test the soil before you add any fertilizer to your common lilacs. Unless the results show a need for a certain nutrient, you probably won't have to fertilize your lilac for several years.
• An excess of nitrogen can harm the plant.

Propagating

• Lilacs readily spread through suckers.
• If you want to propagate the plant, simply dig around a new shoot and cut it from the main plant, taking care not to damage its roots. Then, replant it in a new location and keep it well-watered until its roots take hold.
• However, if you don't want your lilac to spread, just trim off any suckers to keep it under control.

Pruning the Common Lilac

Lilacs require good air circulation to deter certain diseases. Pruning can achieve this, as well as help to maintain the shape, size, and general health of the plant. Common lilacs can reach anywhere from 12 to 16 feet tall and 8 to 12 feet wide, depending on which variety you plant. They generally grow in round, oval, and irregular shapes.

These plants typically bloom for three to four weeks in late spring, though this can vary depending on the variety. The ideal time to prune is just after the blooming period is over. Lilacs bloom on the previous year’s growth, so you want to give a plant plenty of time during the season to grow and set buds. 

Lilacs fall under the general guideline to prune a third of the shrub each growing season. Take off any dead or diseased wood, as well as the spent flowers. Also, remove stems that are thicker than two inches in diameter to prevent the plant from becoming too tall. And prune the remaining stems to create the shape you desire. 

Pests and Diseases

Lilacs can fall prey to several pests and diseases, though certain varieties are more hardy than others. Potential threats include:

Common lilac pests:

• Aphids (Aphididae family)
• Citrus nematode (Tylenchulus semipenetrans)
• European fruit lecanium (Parthenolecanium corni)
• Fuller rose beetle (Asynonychus godmani)
• Ground mealybug (Rhizoecus kondonis)
• Lilac borer (Podosesia syringe)
• Mice (Murinae subfamily)
• Oystershell scale (Lepidosaphes ulmi)
• Voles (Arvicolinae subfamily)

Common lilac diseases:

• Armillaria root rot (Armillaria mellea)
• Bacterial blight or canker (Pseudomonas syringae pv. syringae)
• Botryosphaeria spp. (causes fungal dieback)
• Botrytis blight (Botrytis cinerea)
• Gray mold
• Nectria spp. (causes fungal dieback)
• Phomopsis spp. (causes fungal dieback)
• Phytophthora spp. (causes fungal dieback)
• Powdery mildew (especially prevalent in common lilacs)
• Tubercularia spp. (causes fungal dieback)
• Verticillium wilt (Verticillium spp.)

The best defense against these pests and diseases is to provide your lilac with optimal growing conditions. Check your plant regularly for problems, and treat or cut off diseased areas as soon as you spot them.

Landscape Design for the Common Lilac

Lilacs can be a wonderful addition to your landscape, and there are hundreds of lilac varieties available in an array of colors, including:

• 'Albert F. Holden' (deep violet)
• 'Andenken an Ludwig Spaeth' (purple)
• 'Avalanche' (white)
• 'Beauty of Moscow' (double white with pinkish-lilac)
• 'Belle de Nancy' (double pink)
• 'Blue Skies' (lavender-blue)
• 'Charles Joly' (double magenta)
• 'Katherine Havemeyer' (double lavender, purple, or pink)
• 'Krasavitsa Moskvy' (pale pink)
• 'Leon Gambetta' (double purple)
• 'Miss Ellen Willmott' (double white)
• 'Madame Lemoine' (double white)
• 'Monge' (reddish-purple)
• 'President Grevy' (double lavender-blue)
• 'President Lincoln' (lavender-blue)
• 'Primrose' (yellow)
• 'Sensation' (purple)
• 'Wedgewood Blue' (blue)
• 'Wonderblue' (sky blue)
• 'Yankee Doodle' (purple)

Often used as a specimen plant, lilacs are commonly used as screens and hedges. Dwarf lilacs, which generally reach around three to four feet tall, are great for small gardens and can even be grown in containers. Lilacs can attract bees, birds, butterflies, and other pollinators to your garden. 

If you plant multiple varieties of lilacs in your garden, consider selecting those that bloom at different times. This way, you might be able to enjoy six weeks or more of blooms throughout the spring. Many gardeners prefer to plant their lilacs near a window, patio, or pathway where they can enjoy the scent of the fragrant blooms.