Common Lilac

Syringa vulgaris

Oleaceae

• Full sun (at least 6 hours for best bloom)
• Mature Size: 7–9' wide x similar height (can reach 12–16' if left unpruned)
• Drought Tolerance: Moderate once established; benefits from deep watering during dry spells in the first two seasons
• Flower Color: Purple to lavender-blue (white in some forms); (April–June)
• Wildlife Benefits: bees, butterflies, hummingbirds, and moths visit the flowers; caterpillars of several moth species feed on the foliage; dense branching offers cover for birds

Common lilac is native to rocky hillsides in the Balkans and has been in cultivation since the late 1500s, brought to North America by early colonists in the 1600s; it is the parent species behind essentially all modern lilac cultivars. It performs best in colder climates that provide a long winter chill period for flower buds to mature, and it thrives in Spokane's climate and clay-tolerant, well-drained soils, avoiding only strongly acidic or waterlogged sites. It is not fussy about soil type but does need good air circulation and full sun for the best bloom and to reduce disease pressure.

Large, cone-shaped flower clusters in shades of purple to lavender-blue open in mid-spring, filling the surrounding garden with the classic, powerful lilac fragrance the species is famous for. Heart-shaped, blue-green leaves provide a soft backdrop through the growing season on a multi-stemmed shrub that can become leggy and open with age if not periodically renewed by pruning.

The fragrant flowers are an important nectar source for long-tongued bees, butterflies, and hummingbirds, and the foliage hosts the caterpillars of several moth species; the shrub's dense branching also provides cover for nesting and roosting birds.

A dependable specimen, screen, or informal hedge plant, and one of the most requested shrubs for cut-flower and cottage gardens. For best long-term performance, note for customers: prune immediately after flowering (buds for next year set shortly after bloom, so later pruning sacrifices the following spring's flowers), thin the oldest stems at the base every few years to control legginess and improve airflow, remove rootstock suckers on grafted plants, and watch for powdery mildew, which is common on lilac and worsens with poor air circulation.