The lilac bush (Syringa vulgaris) is a hardy, low-maintenance outdoor plant known for its fragrant flowers that come in a range of colors from blue or purple, to pink and even white. The flowers emerge in panicles (branching clusters) in the early spring, making them a favorite shrub for beneficial pollinators before other flowering plants emerge.
Lilacs are easy to care for once they are established. Certain varieties can grow up to 30 feet tall and offer suitable shade. With proper care, your lilac can live for several decades, making it a long-lasting addition to your garden.
Lilacs do best when planted directly into the ground, but dwarf varieties can be kept in pots until they grow too big. You can grow lilacs from seeds or cuttings. The easiest and most popular way to grow new lilac plants is from runners taken from existing plants.
The best time of year to plant lilacs is in the early fall before the first freeze or in the early spring after the ground thaws. Lilacs do best in well-drained but moist soil with a neutral to alkaline pH (6.5 to 7.0). Prepare a hole at least twice the width and as deep as your lilac’s root ball. Place the root ball in the hole, then fill and pack soil around it. The root ball should be about an inch above the soil level. Water thoroughly around the base of the lilac. You can add mulch around your new plant, but take care not to place too much directly around the trunk.
Lilacs thrive in full sun for at least 6 to 8 hours per day. Avoid placing this plant adjacent to a tree, your house, or another structure that might block its ability to receive sunlight. Lilacs can grow in partial shade, but they won’t fare as well, and this will limit their ability to bloom.
Lilacs do well with infrequent watering as they do not like wet feet. Overwatering will lead to a lack of blooms and drooping, pale, or yellow leaves. However, a new plant needs moist soil to get established. Water once or twice a week (or whenever you notice the top inch of soil begins to get dry). After several months, you can water less frequently (once every 10 to 14 days).
Lilacs require the most watering during the spring when they are in bloom. Make sure to always water at the base of the plant and never overhead as this can damage blooms.
After planting, lilacs usually do not need additional nutrients. A 10-10-10 fertilizer is appropriate to apply at the base of your lilac just before spring, but you should not need to fertilize otherwise. Too much nitrogen will result in excessive leaf growth. A balanced fertilizer ensures that you do not get heavy blooms or too much foliage.
Lilacs are deciduous shrubs that grow in USDA hardiness zones 3 through 9. The common lilac prefers zones 3 through 7 — areas susceptible to cold winters, like the Midwest — as well as places with milder winters, like the Pacific Northwest and the Mid-Atlantic regions. Some species can grow in zones 8 and 9, thriving in California, Texas, and the South.
Pruning lilacs promotes flowering and establishes air circulation around the plant, helping to ward off common problems like powdery mildew. The optimal time to prune is after they bloom in spring. Deadhead spent flowers, remove older branches that aren’t producing as many blooms, and take out any dead or diseased branches and broken stems.
Choose hand pruners over shears or other tools. Cut back to just above a new node where possible and sterilize your pruners before moving from one plant to another, as spreading disease is a common concern with lilacs.
The hardy lilac bush can generally withstand cold temperatures but there are a few ways you can give them extra protection. Winterizing your lilac by deadheading spent flower heads and adding 3 to 4 inches of organic mulch to the base of the shrub. If freezing weather is in the forecast, cover the shrub with a tent, blanket, or a burlap sack for added protection.
When you want to propagate from your existing lilac bush, it’s best to take a few cuttings from new growth either in the late spring or the early summer. Newer growth has a better chance of rooting.
Lilacs are susceptible to powdery mildew, a white fungal growth that appears on leaves when the weather is hot and humid. Remedies include applying a fungicide, removing affected leaves, and increasing air circulation around infected areas. Bacterial blight is another common malady that causes leaf spots that change from green to brown. Thwart further blight by pruning infected branches, thinning the inside of the bush, or applying a bactericide.
The most common pests for the lilac include caterpillars and leaf miners. Scales and borers present more of a problem. Treat scales with multiple applications of neem oil. If they form around one part of the lilac, you can prune away the infected branches. Borers live inside of the lilac along its stems and branches. The most effective way to prevent a borer infestation is to make sure your lilac is healthy. The healthier the plant, the less susceptible it is to attracting pests.
In addition to being a stunning addition to a garden, lilacs are well-suited for hedgerow planting, where they act as a privacy screen. Lilacs also add a colorful pop to floral arrangements. Take cuttings in the morning while the stems are hydrated. Prepare a vase with water and make sure your blooms are placed in a location that will receive indirect sunlight. Recut the stems at a 45-degree angle and replenish water as needed to prevent them from wilting. Dried blooms are a great addition to potpourri or sachets.
Lilacs are part of the olive family (Oleaceae), which also includes the ash tree, forsythia, jasmine, and privet. The crepe myrtle, otherwise known as the Southern lilac, most closely resembles the lilac in its appearance. Other plants with similarities to lilacs include buddleia and hyacinth.
Lilacs are not poisonous, but if pets consume any part of the plant in significant amounts, they may get sick. If a lilac is growing too close to your home or another structure, you may need to remove it permanently. Cut it as close to the ground as possible and place herbicide on top to ensure it doesn't grow back.
The common lilac might be the most recognized variety, but there are several other types you can choose from—over 1,000, in fact. The Dwarf Korean Lilac and the Wedgewood Blue Lilac are both ideal in smaller garden spaces because they generally don’t grow higher than six feet. The Persian lilac’s pale pink blooms attract pollinators, while Japanese tree lilacs can grow up to 30 feet tall and spread as wide as 20 feet.