There are a few lilac species that are available at garden centers. These can be segregated into three groups, 1) the “old-time” very fragrant large upright shrubs that your grandmother grew; this is the common lilac (Syringa vulgaris); 2) the more densely branched shrub type; there are two species of this description; these are Meyer lilac (Syringa meyeri) and the Manchurian lilac (Syringa pubescens subsp. patula; previously named S. patula); 3) the tree forms, these are Japanese tree lilac (Syringa reticulata) and the Pekin lilac (S. reticulata subsp. pekinensis previously S. pekinensis). Each of these lilacs have a particular flowering time, ranging from April through June, so if one chooses to have a very long lilac blooming period, then they can plant all of these species. All garden lilacs are deciduous. A summary of each of the species will be given.
Large Upright Shrub Lilacs
Main features: The common lilac has been used as a garden plant since the 16th century. The most notable feature is the showy very fragrant flowers in April (May). Flowers are commonly brought indoors for floral arrangements as well as to perfume the household. The common lilac is represented by an enormously long list of cultivars (about 2,000). Cultivar selection criteria are flower characteristics (color, fragrance, single/double flowers), disease resistance, tendency to sucker, and size. Flower color (white, violet, blue, lilac, pink, magenta, and purple) and fragrance, as well as single or double flowers, are a matter of personal preference. Many of the cultivars are susceptible to powdery mildew, a fungus that makes the leaves look white and lessens the vigor of a plant. The tendency to sucker will increase the maintenance time to prune of suckers to control plant size. Most cultivars are large shrubs (taller than 8 feet) but there are a few cultivars that are medium shrubs (4 to 8 feet tall). The common lilac is not suited to the heat of the south; the recommended growing areas for this species are zones 3 to 7; plants will languish in hot portions of zone 7. Lilacs tolerate drought and poor soils (once established) and require a full sun exposure. They do require pruning; un-pruned older plants will get leggy and unsightly. There are two pruning strategies to rejuvenate a common lilac: 1) every year remove about one-third of the largest stems, or 2) cut the entire plant down to about 1.5 feet above ground level. If you choose option 2, then the following spring your plant will not flower or only have a few flowers depending when you prune it. Lilacs are best pruned right after they flower. To get an idea of the cultivar you should use in your garden/landscape, keep the aforementioned cultivar selection criteria in mind and visit web sites that have photos and descriptions of the cultivars.
Densely Branched Shrub Type Lilacs
Meyer lilac is a dense multi-stem medium to large shrub (about 8 feet tall and 12 feet wide) and is quite spectacular in flower. This dense habit makes it much more handsome than an old un-pruned common lilac. Additionally, this species does not require rejuvenation pruning as does the common lilac. Meyer produces showy fragrant flowers in April that start out violet purple and fade to pink. This species does not sucker or get powdery mildew (as does the common lilac); it requires little care, tolerates drought and poor soils, and requires a full sun exposure. Meyer lilac is adapted to zones 3 to 7. ‘Palibin’ is a very popular cultivar due to its compact habit.
Syringa pubescens subsp. patula (previously named S. patula)
Manchurian lilac is a dense multi-stem medium to large shrub (about 8 feet tall and 12 feet wide) and is quite spectacular in flower. This dense habit makes it much more handsome than an old un-pruned common lilac. Additionally, this species does not require rejuvenation pruning as does the common lilac. Manchurian lilac produces showy and intensely fragrant pink flowers in May. This species does not sucker or get powdery mildew (as does the common lilac); it requires little care, is somewhat tolerant of drought and poor soils, and requires a full sun exposure. Manchurian lilac is adapted to zones 4 to 7. ‘Miss Kim’ is a very popular cultivar due to its compact habit.
Tree Form Lilacs
Japanese Tree Lilac
The Japanese tree lilac is a large shrub or small tree (about 25 feet tall). This species produces showy cream-white fragrant flowers in June (May in southern zones). Like other lilacs, Japanese tree lilac tolerates drought and poor soils; like Meyer lilac, this species is resistant to powdery mildew. It can be used in zones 3 to 7 but will languish in the hot portions of zone 7. There are a few cultivars offered in the trade; ‘Ivory Silk’ is one of the most popular cultivars since it has a compact dense form that produces a large amount of flowers even at a young age.
S. reticulata subsp. pekinensis previously named S. pekinensis
Pekin lilac is a large shrub/small tree species that produces showy cream-white fragrant flowers in June. It is suited to zones 4 to 7. Some cultivars (commercial clones) have a showy exfoliating lustrous brown bark such as China Snow® and Summer Charm®. Beijing Gold® has yellowish flowers. China Snow® is the showiest due to its exceptional lustrous amber-brown bark that exfoliates in long papery curly swirls; this clone rivals paperbark maple (Acer griseum) for bark effect. Pekin lilac tolerates drought and poor soils.
Virginia Cooperative Extension materials are available for public use, reprint, or citation without further permission, provided the use includes credit to the author and to Virginia Cooperative Extension, Virginia Tech, and Virginia State University.
Issued in furtherance of Cooperative Extension work, Virginia Polytechnic Institute and State University, Virginia State University, and the U.S. Department of Agriculture cooperating. Edwin J. Jones, Director, Virginia Cooperative Extension, Virginia Tech, Blacksburg; M. Ray McKinnie, Administrator, 1890 Extension Program, Virginia State University, Petersburg.
November 3, 2010