Plants of History—Plants for Tomorrow
When you plant a lilac in your garden you are choosing a shrub that is part of this country’s history. In 1767, for example, Thomas Jefferson recorded his method of planting lilacs in his Garden Book, and on March 3, 1785, George Washington noted that he had transplanted existing lilacs in his garden. The oldest living lilacs in North America may be those at the Governor Wentworth estate in Portsmouth, N.H., believed to have been planted around 1750.
Lilacs are part of New England’s horticultural heritage, but like much of the region’s diverse citizenry, are not native to North America. Of the 20-plus species of lilacs, two derive from Europe and the others are from Asia. The common lilac (Syringa vulgaris) originated in eastern Europe. This species and hybrids of it were so frequently grown and selected by French nurserymen that France became synonymous with fine lilacs; we know them today as “French hybrids.”
Most lilac species hail from Asia, including two of the most popular choices for the contemporary landscape, Syringa patula ‘Miss Kim’ and S. meyeri ‘Palibin.’ The compact, later flowering ‘Miss Kim’ is noted for its intense fragrance; the neat growth habit of ‘Palibin’ fits well in the modern garden.
Known as plants for colder climates, lilacs need a period of cold-initiated dormancy to trigger flowering. New selections of lilacs are offered by hybridizers across the north temperate zone which includes Europe and most of North America and Asia. Today, lilac selections originate from across the globe and are sold under a variety of names. The cultivar epithet (name) surrounded by single quotes is published by the International Lilac Society who manages global registration.
The Arnold Arboretum’s collection of lilacs is one of the oldest and largest in North America, but lilacs on our grounds predate the 1872 founding of the institution. Benjamin Bussey probably planted lilac hedgerows soon after he acquired the land in 1806. We have taken cuttings of the remnants of his lilacs, and have recreated hedgerows on the east side of what is now called the Explorers Garden on Bussey Hill.
Our Lilac Sunday festival, celebrated the second Sunday in May, has become a tradition of its own. Attendance on any given Lilac Sunday is difficult to estimate, but one noteworthy peak occurred in 1941, when 43,000 people are said to have visited.
How To Plant And Care For Lilacs
Lilacs grow best in full sun and well-drained soil. Lilacs grown in partial sun or shade will not flower well. The shrubs may take three to four years to establish themselves in a new site, but once established they can live for centuries. Soil pH (alkalinity or acidity of the soil) may affect the plant’s growth. Lilacs do well in a slightly acid to alkaline soil. New England soils are often very acidic and may require some modification for best lilac growth.
To ensure abundant flowering, cut off all spent blossoms each year and prune the flowering stem back to a set of leaves, thus preventing seed formation. If this is not done, good flowering years may be followed by bad years. Since flower buds are formed the summer before they bloom, winter pruning will remove them.
Remove dead, damaged, or diseased branches. Tall, leggy, poorly flowering plants require renewal pruning; remove about one-third of the oldest stems at ground level each year for three years. This encourages growth of vigorous new stems from the base. By the end of three years the plant should be fully rejuvenated with blossoms once more at nose level.
Tough as lilacs are, they do need ample water as they establish. Lilacs thrive in moist but well-draining soil.
In our area the most serious lilac problems are powdery mildew fungus (Microsphaera alni), lilac borer (Podosesia syringae) and scale (oyster-shell scale, Lepidosaphes ulmi and prunicola scale, Pseudaulacaspis prunicola). Powdery mildew looks like whitish patches dusting the leaves. It is unattractive but in our climate is rarely serious. Borers leave 1/8-inch holes in stems and larger branches, often one to two feet above ground level. A minor infestation might be ignored, but more than a few borers should be diagnosed and treated by a professional. Oyster-shell scale is aptly named, as the pests look like 1/8-inch oyster shells on the stems, while prunicola scale covers bark with a dusty white mass. Control adult scale by pruning heavily infested branches; control tiny young “crawlers” with a hard spray of water from a garden hose (use a hand lens to see scale). Dormant oil and summer oil are also effective.
Lilacs offer many opportunities to the garden designer. Plant a flowering hedge of the compact Syringa meyeri ‘Palibin’, or, for a striking accent, choose a standard form. Place a bench in the fragrant shelter of ‘Miss Kim,’ or bring a touch of New England tradition to a modern landscape with the great French hybrids ‘Mme Lemoine’ or ‘President Grevy’. And remember that lilacs span a rainbow of colors, from rich reds, blues, and purples to romantic pinks, whites, mauve, and the delicate, creamy yellow of ‘Primrose’.
The best of the best lilacs, in our definition, should be highly fragrant, display many flowers at eye (and nose) level, resist mildew and leafroll necrosis, and produce new growth that does not obscure the flowers and enough suckers to replace old or injured stems. Ideally, the gardener should be able to find the perfect lilac in every flower color, for every season of bloom, in both single and double form.
The following lilacs reach peak bloom during New England’s traditional lilac time-the second through the fourth week of May. This list includes only cultivars of Syringa vulgaris and the early flowering S. x hyacinthiflora, which have the general appearance of the traditional or common lilac.
Syringa vulgaris and Syringa x hyacinthiflora Cultivars
Key: single flowered (S); double flowered (D); high degree of fragrance
(F); early blooming hybrid (E)
|Henri Robert (D), Mechta (S)
|President Lincoln (E, S), Wonderblue (a.k.a. Little Blue Boy) (S)
|Sarah Sands (S), Albert F. Holden (S)
|Katherine Havermeyer (E, D), Lucie Baltet (S), Mme. Antoine Buchner (D), Maiden’s Blush (F, S), Marie Frances (S)
|Asessippi (E, F, S), Excel (E, F, S), Michel Buchner (D), Lilac Sunday (S)
|Krasavitsa Moskvy (D), Sister Justina (E, S)
|Arch McKean (F, S), Paul Thirion (D), Ruhm von Horstenstein (S)
Syringa x chinensis ‘Lilac Sunday’
This new cultivar from the Arnold Arboretum was grown by former plant propagator Jack Alexander from seed supplied by the Beijing Botanical Garden. The pale purple flowers are fragrant, appearing in mid May, and offering an abundant display annually. Although the individual flowers are small, they are produced in panicles not only at the branch tips, like the common lilac, but also from the lateral buds. The plant has a graceful arching habit and is expected to attain a size similar to that of other cultivars of S. x chinensis, about 12 feet by 12 feet. Please visit the Arboretum during our annual Lilac Sunday festival to view this unique plant.
Ten Favorite Uncommon Lilacs
Though not necessarily rare or hard-to-find, the hybrids and selections of the species listed below have leaves, flowers, and fragrance that are quite different from the common lilacs. These plants offer adventurous gardeners the opportunity to break with tradition.
• S. meyeri ‘Palibin’
• S. pubescens subsp. microphylla ‘Superba’
• S. pubescens subsp. patula ‘Miss Kim’
• S. pekinensis ‘Morton’ China Snow™
• S. ‘Bailbelle’ Tinkerbelle™
• S. (Villosae Group) ‘Miss Canada’
• S. protolaciniata
• S. pubescens
• S. reticulata
• S. villosa ‘Charles Hepburn’
Would a Lilac by Any Other Name Smell So Sweet? A Search for Fragrance
The quest for all-encompassing knowledge of his favorite genus has taken the Arboretum’s plant propagator down many byways. This one required a cadre of volunteers and a high-speed computer.
Read the article here.
This article originally appeared in Arnoldia volume 56, number 1, in 1996.