How to Grow and Care Common Lilac (Syringa Vulgaris)

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.

They 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.

Common Lilac Care

Here are the main care requirements for growing common lilacs:

• Plant in full sun in a loamy, somewhat moist soil.
• Can tolerate periods of drought, but prefers good watering during hot, dry weather.
• Can handle frigid weather but prefers a cool, moderate temperature.
• Benefits from a good pruning.

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.

Types of 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)

Pruning

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. 

Propagating Common Lilac

Lilacs readily spread through suckers. Here's how to propagate them:

1. Dig around a new shoot and cut it from the main plant, taking care not to damage its roots.
2. Replant it in a new location and keep it well-watered until its roots take hold.
3. If you don't want your lilac to spread, trim off any suckers to keep it under control.
   

How to Grow Common Lilac from Seed

Common lilac can be grown from seed, however, the seeds must be harvested first and the process is time-consuming. Here is how to grow common lilac from seeds:

1. Harvest the lilac seed head once the flowers are wilted. Keep in mind seed heads may not be present for up to three years until after the lilac was first planted).
2. When you see clusters of brown, nut-like fruit, wait for it to dry and split open. Here in lies your seeds.
3. Pull seeds from the dried lilac seed pods and store the seeds until you are ready to plant them via propagation.

Potting and Repotting Common Lilac

Common lilac is used as a specimen plant and typically used as screens and hedges. However, dwarf lilacs, which generally reach around three to four feet tall, are great for small gardens and can even be grown in containers.

Overwintering

When preparing your lilac for the winter, be sure to water it deeply to ensure the plant is plenty hydrated before the cold weather hits. Then, keep the base of the plant warm with about 3 to 4 inches of organic mulch. This will prevent the exposure of roots due to the ground freezing and thawing. Once late spring arrives, deadhead the plant to prep it for bloom.

Common Pests and Diseases

Lilacs can fall prey to several pests and diseases, though certain varieties are more hardy than others. Potential threats include aphids, citrus nematode, European fruit lecanium, fuller rose beetle, ground mealybug, lilac borer, oystershell scale as well as mice and voles.

The common lilac is also susceptible to several types of diseases that cause fungal dieback as well as armillaria root rot, bacterial blight or canker, gray mold, powdery mildew (which is especially prevalent in common lilacs), and verticillium wilt. 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.

Lilacs can attract bees, birds, butterflies, and other pollinators to your garden. 

How to Get Common Lilac to Bloom

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.

Bloom Months

Common lilac blooms from April through June.

How Long Does Common Lilac Bloom?

As a perennial, common lilac blooms every year. Its bloom time lasts for about two months.

What Does Common Lilac's Flowers Look and Smell Like?

Flowers from lilacs have a. sweet, strong fragrance and come in a multitude of colors, specifically purple, pink, and white.

How to Encourage More Blooms

Keeping your lilac in full sunlight and pruning it regularly will help to encourage more blooms. Cut lilac one-third of the way back, which will help to regenerate new growth from the bottom.