Lilac (Syringa spp.)

Fundamental Facts

HARDINESS: Zones 2 to 8
PREFERRED SOIL pH: Neutral to slightly acid
PREFERRED SOIL TYPE: Well-drained sandy loam
PREFERRED LIGHT: Sun
ATTRIBUTES: Fragrant white, pink, yellow, or purple flowers; for specimens, hedges
SEASON OF INTEREST: Late spring to fall
FAVORITES: 'Ester Staley', 'Blanche Sweet', 'Sensation', 'Palibin', 'Miss Kim'
QUIRKS: Flowers on old wood
GOOD NEIGHBORS: Azalea, candytuft, crocus, daffodil, forsythia, tulip, perennials
WHERE IT GROWS BEST: In sun, well-drained soil, and cool climates
POTENTIAL PROBLEMS: Powdery mildew, lilac borers
PRUNING: Lives for decades; cut one-fourth of old stems to ground level in winter
CRITTER RESISTANCE: Good
SOURCE: Nursery plants
DIMENSIONS: 4-15 ft (1.2-4.6 m) tall and equally wide

Lilac in the Landscape

Lilacs, like roses, linger in the romantic hearts and memories of gardeners. Often found in older gardens, these long-lived plants with tough constitutions are cherished for their spectacular trusses of fragrant spring flowers. Thousands of cultivars exist, featuring single or double flowers in deep purple, blue, pink, yellow, and white.

Lilacs are excellent plants to locate at doorways or along paths, where the sweet fragrance will greet passersby. Or place them along the edge of the lawn, where they can be planted close enough together to form a hedge. Compact dwarf types can be worked into mixed flower borders or included
in foundation groupings with other shrubs on the sunny side of a house.

World-Class Lilacs

The most fragrant of all lilacs is the common lilac (Syringa vulgaris), whose flowers are usually the pale purple color that gives this shrub its common name. It grows to about 10 ft (3 m) tall and has numerous cultivars, ranging from the old-fashioned double white 'Mme. Lemoine' to the dark violet 'Night'. Some have bicolored blossoms, such as 'Sensation', whose purple-red florets are edged in white.

Common lilac requires a period of winter freezing to set flower buds, and seldom flowers well in areas with hot, humid summers and mild winters. But two lilacs developed from Chinese species show better heat tolerance. S. meyeri 'Palibin' is a slow grower with dense trusses of lilac-pink blossoms. S. patula 'Miss Kim' has fragrant flowers that are purple in bud and fade to a blue-tinged white. Both grow less than 4 ft (1.2 m) tall and bloom well even in Zones 7 and 8. In climates with cold winters, look for cultivars of S. x hyacinthaflora, such as 'Blanche Sweet' and 'Esther Staley'. These bloom early in spring with a distinct sweet fragrance, are resistant to powdery mildew disease and boring insects, and are hardy to Zone 3. Another hybrid that has made a big splash in cold-climate gardens is the 10-12 ft (3-3.7 m) tall S. x prestoniae, represented by the bright pink-flowered 'Miss Canada' and claret-colored 'Redwine'. Developed in Canada, these are hardy even in Zone 2.

Growing Lilac

Select a site that receives at least 6 hours of sun daily and has good air circulation. These are both important conditions for limiting problems with fungal leaf diseases, which erupt in damp, stagnant air. Plant container-grown or bare-root plants in late winter or early spring. Container-grown plants set out after they have emerged from dormancy need attentive watering to keep the soil around the roots moist if their first summer in the garden is a dry one.

Once established, lilacs respond to fertilizing with a balanced, timed-release commercial product, or top-
dressing of compost in spring. In acid soils, it is also helpful to sprinkle garden lime on the soil above the roots, according to package directions, every 3-4 years to neutralize the pH.

Prune lilacs to improve flowering, promote good air circulation, and discourage powdery mildew and boring insects, which weaken the plants. Remove damaged or diseased stems as soon as you notice them. In midwinter, cut out about one-fourth of the oldest, largest stems as close to the ground as possible. Also snap off any suckers, which are stems growing up from the base of the plant.

Branches that have small holes with sawdust around the openings harbor boring caterpillars; in summer, they cause stems to wither and die. Cut the stem 1 in (2.S cm) below the hole and dispose of it, or insert a thin wire into each hole to kill the pests.