Lilacs: How to Plant, Grow, Prune, and Care for Fragrant Shrubs

Huge blooms, wonderful scent.

Wally Patrick

Where to buy lilacs: Burpee Gardening

Who doesn't love lilacs? The ideal lilac shrub has ~10 canes with flowers at eye-level—perfect for enjoying that sweet, haunting fragrance.

Lilacs come in seven colors, but most know common lilac, Syringa vulgaris, blooming 2 weeks in late May in northern states. Early-, mid-, and late-season lilacs together ensure steady bloom for ≥6 weeks.

Lilacs are hardy, easy, low-maintenance. Height: 5–15 feet by variety. Fragrant flowers good for cutting, attract butterflies.

Planting Lilacs

• Grow in fertile, humus-rich, well-drained, neutral to alkaline soil (pH ~7.0). Poor soil: add compost.
• Full sun—≥6 hours. Insufficient sun = poor bloom.
• Site must drain well. Lilacs hate wet feet and won't bloom with excess water.
• Plant spring or fall (fall preferred).
• Friend's sucker/offshoot? Dig hole, backfill, plant sucker. Water and wait. In 4–5 years: huge fragrant blossoms.
• Nursery transplants easy. Container-grown: spread roots settling in. Balled/burlapped: gently remove rope. Plant 2–3 inches deeper than nursery, work topsoil around roots. Water, then fill hole.
• Space multiple shrubs 5–15 feet apart by variety.

Care

• Each spring: compost layer + mulch for moisture/weed control.
• Water summer if rainfall <1 inch/week.
• Lilacs won't bloom if overfertilized. Handful of 10-10-10 in late winter max.
• After bloom: spread lime + well-rotted manure around base. Trim for shape, remove suckers.

Pruning Lilacs

• Lilacs bloom on old wood—prune in spring right after bloom. Summer pruning removes next year's wood. Tip: If flower clusters shrink, time to prune!
• Yearly after bloom: remove dead wood. Prune oldest canes to ground. Remove small suckers. Cut weak branches to strong shoot. Cut tall canes to eye height.
• Old, bad shape: remove ⅓ oldest canes (ground) year 1, half remaining old wood year 2, rest year 3. Or drastic: chop to 6–8 inches. Lilacs are very hardy. Downside: few years to regrow. Upside: less work, more reward—bursts with blooms.
• Severe pruning loses blooms 1–3 years. Wise program: annual attention avoids drastic cuts.

Pests and Diseases

• Slugs and snails.
• Powdery white mildew after hot, humid summers. Unsightly but harmless. Ignore it.

Recommended Varieties

Most common/fragrant: S. vulgaris:

• Early bloom: 'Charles Joly' — double magenta.
• Mid-season: 'Monge' — dark reddish purple; 'Firmament' — fine blue.
• Late-season: 'Miss Canada' — reddish-pink; 'Donald Wyman' — single purple.

Common lilacs love cold, but some thrive to Zone 9: cutleaf lilac (fragrant pale lavender). Syringa patula 'Miss Kim' — graceful, pale lilac-blue fading to white.

Wit & Wisdom

• Improve flowering: keep grass from growing around them. 16–24 inch landscape cloth circle + bark/stone keeps grass down.
• Force winter bouquet from cut branches. Bruise cut ends, set in water. Spray frequently. Cool place until bloom, then warmer for display.
• Walt Whitman on lilacs at Lincoln's death: "When lilacs last in the dooryard bloom'd … I mourn'd, and yet shall mourn with ever-returning spring."
• Lilacs symbolize joy of youth. Learn more flower symbolism.