How to Grow a Lilac Shrub (2024)

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Lilacs thrive in fertile, humus-rich, well-drained, neutral to alkaline soil (at a pH near 7.0). If your soil is in poor condition, mix in compost to enrich it. (Learn more about soil amendments and preparing the soil for planting.) Choose or prepare a site that drains well. Poor drainage or pooling water can cause “wet feet,” potentially leading to root rot, stunted growth, and/or failure to flower. Test soil drainage by digging a hole 8 inches in diameter and 12 inches deep. Fill it with water; if it does not drain within an hour, choose anotherspot.

For the best blooms, lilacs should be planted in full sun, which is defined as being at least 6 hours of sunlight each day. Given less, they will not flower aswell.

When to PlantLilacs

• Like most shrubs, lilacs can be planted in either spring or fall, although the latter ispreferred.

How to PlantLilacs

• 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, fragrantblossoms.
• 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, gentlyremove the covering and any rope before planting.Set the plant 2 or 3 inches deeper than it grew in thenursery, and work topsoil in around the roots—water in. Then, fill in the hole with moretopsoil.
• Space multiple lilac bushes5 to 15 feet apart, depending on thevariety.

• Each spring, apply a layer of compost under the plant, followed by mulch to retain moisture and controlweeds.
• Water during the summer if rainfall is less than 1 inch perweek.
• Lilacs won’t bloom if they’re overfertilized. They can handle a handful of 10-10-10 in late winter, but nomore.
• After your lilac bush has finished blooming, spread some lime and well-rotted manure around the base. Trim the bush to shape it and remove suckers at the sametime.

How to Prune Lilacs: PruningLilacs

• Lilacs bloom on old wood, so it’s critical to prune in the spring right after they bloom. If you prune later in the summer, you may be removing the wood. Note: If your lilac flower clusters are getting smaller over a few years, it’s time toprune!
• Every year after bloom, remove any dead wood. Prune out the oldest canes (down to the ground). Remove the small suckers. Cut back weak branches to a strong shoot. Cut back tall canes to eyeheight.
• The ideal lilac shrub has about 10 canes. If your lilac is old and in really bad shape, remove one-third of the oldest canes (down to the ground) in year one, half of the remaining old wood in year two, and the rest of the old wood in year three.Another option for old lilacs is to chop the whole thing back to about 6 or 8 inches high. It sounds drastic, but lilacs are very hardy. The downside to this option is that it takes a few years to grow back. The upside is less work and more reward, as the lilac will grow back, bursting withblooms.
• It must be recognized that severe pruning results in the loss of blooms for one to three years. For these reasons, a wise pruning program aims to avoid severe and drastic cuts by giving the bushes annualattention.
• Good Sucker Sense: Gertrude Jekyll, the 19th-century no-nonsense English horticulturist (1843– 1932), advocated a strenuous exercise: “When taking away suckers … it is better to tear them out than to cut them off. A cut, however close, leaves a base from which they may always spring again, but if pulled or wrenched out, they bring away with them the swollenbase.”

For early flowers, try Syringa x hyacinthiflora hybrids; they bloom 7 to 10 days before S. vulgaris. It’s fragrant blooms attract butterflies andhummingbirds.

The most common and fragrant lilacs are of the Syringa vulgaris variety:

• Try ‘Charles Joly’, a double magenta flower, an earlybloomer.
• Mid-season lilacs include ‘Monge’, a dark reddish purple, and ‘Firmament’, a fineblue.
• Late-season beauties include ‘Miss Canada’, a reddishpink, and ‘Donald Wyman’, a pink-purpleflower.

Uncommon types/varieties include…

• S. x ‘Penda’ Bloomerang Purple: flowers in spring, pauses, then flowers again from midsummer throughfall
• Although common lilacs love cold weather, a few thrive as far south as Zone 8, including cutleaf hybrid S. x laciniata, with fragrant, pale lavender flowers, and S. pubescens ssp. patula ‘Miss Kim,’ with pale, lilac-blue blooms that fade towhite.

Small Lilacs
For gardeners, especially those in urban spaces, who just don’t have the room for the traditional larger lilac, there are compact varieties! They’ll even grow in a container on your patio orbalcony.

• ‘Baby Kim’ grows only 2 to 3 feet high (and 3 feet wide) in a nicely rounded shape with purple flowers that attract butterflies. Extended hardiness from Zones 3 to8.
• ‘Little Lady’ (Syringa x) is a compact lilac that matures to 4 to 5 feet tall and wide with dark pink buds that open to lilac-pink flowers. Hardy in Zones 2 to7.
• ‘New Age Lavender’ and ‘New Age White’ (Syringa vulgaris) are super-compact, growing from 4 to 5 feet tall and wide, and bred for mildew resistance. Their fragrant flowers attract butterflies and hummingbirds. Hardy to Zone4.

See more lilac varieties!

Catherine Boeckmann