One of the most recognizable shrubs for its flowers and their intoxicating fragrance, lilacs are stately shrubs perfect for shaking off the winter grogginess and building excitement for the warmer months to come. Belonging to the olive family, Oleaceae, Syringa (sih-REEN-gah) is a genus of twelve species, native to southeastern Europe and eastern Asia and cultivated in temperate areas worldwide. Ranging from small shrubs to nearly tree-sized in stature, lilacs are commonly available in cultivars of common lilac, dwarf Korean lilac, Korean lilac, Preston lilac, and hybrid reblooming lilacs.
Blooming throughout the spring and summer depending on species, lilac develop profuse panicles of many fragrant, tubular flowers with four-lobed corolla (fused petals). Flowers are available in a wide array of colors, including nearly every shade of purple, pink, and soft blue, as well as white, and are excellent sources of nectar for hummingbirds, butterflies, and other visiting long-tongued pollinators. For all species, blooms should be removed where practical after fading to avoid wasting energy for seed production, and plants should also be pruned at this time if desired, as most species begin forming next spring’s buds shortly after blooms expire. All species will generally thrive in moist, well-drained soils in full sun, are intolerant of shady conditions or wet sites, and are deer and rabbit resistant.
The first and the longest lasting of the lilac blooms, the beloved common lilac, Syringa vulgaris, is a large upright shrub, maturing to heights upwards of 8-12’ tall and 6-8’ wide with great drought tolerance once established. Blooming intensely fragrant flowers from mid-spring to early summer on old wood (the previous season’s growth), common lilacs make excellent sunny specimens and foundation plantings, and work wonderfully as a hedge or privacy screen when massed in rows.
Blooming slightly later from late spring to early summer, the Korean lilac, Syringa pubescens subsp. patula, including the beloved ‘Miss Kim,’ is a more compact shrub, reaching 5-8’ tall and wide. Blooming on old wood, Korean lilacs have slightly smaller yet very dense flower panicles with fragrant blooms excellent for foundation plantings and shrubby borders. Korean lilacs also have lush disease resistant foliage that later takes on rich burgundy fall color.
Dwarf Korean lilac, Syringa meyeri, also blooming from late spring to early summer, is an excellent compact dwarf shrub that matures to an attractive mounded form of 4-5’ tall and 5-6’ wide, typically sold as the popular ‘Palibin.’ Unlike the common or Korean lilac, Syringa meyeri often lightly reblooms in mid to late summer on new wood, in addition to their abundant flush of spring blooms produced on old wood. The smaller stature and compact form of dwarf Korean lilac make them excellent candidates for foundation plantings and low shrubby borders, including below windows where other shrubs may obstruct views. Salt tolerant and somewhat drought tolerant once established, their disease resistant foliage later takes on excellent amber fall color as well. Dwarf Korean lilac are also commonly grafted onto a standard stock to act as small garden trees maturing to about 5-7’ tall and wide.
Offering an exciting new take on the classic lilac, reblooming lilac hybrids, including the iconic Bloomerang® series, offer abundant lilac blooms on new and old wood. Ranging in size from 3-6’ tall and wide in a rounded form of disease resistant foliage, reblooming lilacs bloom profusely in the late spring on old wood. Fragrant blooms are produced on both compact and dwarf habits and are followed by a flush of foliage growth before reblooming lightly from mid-summer to late summer or early fall.
The Preston lilac, Syringa x prestoniae, is a notably hardy hybrid of S. reflexa and S. villosa, boasting exceptional hardiness down to USDA Zone 2. Well-adapted to cold climates, the Preston lilac, unlike other species mentioned above, blooms only on new spring growth, meaning their buds are not prone to winter or frost damage and will bloom in the early summer, slightly later than other lilacs. Preston lilac is the only lilac of these species that should be pruned in early spring before leafing out, though spent blooms should still be removed. Preston lilacs are large shrubs reaching upwards of 8-12’ tall and wide with great salt tolerance. Fragrant blooms including the rosy pink of ‘Miss Canada’ and its non-suckering habit make Preston lilacs excellent for foundation plantings or flowering hedges, offering a great large alternative to the gently suckering common lilac as well.