Japanese Lilac Tree Seeds | Tree Lilac | (Syringa reticulata)

The lilac that grew into a tree. Fragrant white flowers in June when everything else is done.

Syringa reticulata, the Japanese Tree Lilac, is the largest member of the lilac family and the only one that grows into a true tree form, reaching 25 to 30 feet with a single trunk and an oval crown rather than the multi-stemmed shrub habit of its relatives. It blooms in late May and June, weeks after common lilacs have finished, producing enormous creamy-white flower clusters that can reach 12 inches long and fill the surrounding air with a scent that is more subdued and honey-like than common lilac. Its cherry-like bark, with prominent horizontal lenticels, is attractive in every season. Cold-hardy, pest-resistant, and adaptable to a wide range of soils and urban conditions, it is one of the most reliable and underused small flowering trees in North American horticulture. If you are looking to buy Japanese Tree Lilac seeds or grow this late-blooming native-range tree from seed, this fills the early summer flowering gap when almost nothing else is in bloom.

• Enormous creamy-white flower clusters in late May and June, weeks after common lilac finishes
• Grows into a true tree form with a single trunk unlike all other lilac species
• Cherry-like bark with horizontal lenticels attractive in every season
• Cold-hardy to zone 3, one of the most cold-tolerant flowering trees available
• Highly resistant to powdery mildew and lilac borers that affect common lilac

Things you probably did not know about the Japanese Tree Lilac

It is the most cold-hardy large flowering tree available in zone 3. Most ornamental flowering trees with showy bloom displays are limited to zones 5 or warmer. Japanese Tree Lilac performs beautifully in zones 3 and 4, bringing a late spring floral display to climates in northern Minnesota, Canada, and other harsh-winter regions where most flowering trees simply cannot survive.

The fragrance is distinctly different from common lilac. Japanese Tree Lilac fragrance is described as honey-sweet, privet-like, and less intensely sweet than common lilac. Some people find it more pleasant than common lilac precisely because it is less overwhelming. The fragrance carries well in evening air and attracts a wide range of pollinators including native bees, swallowtail butterflies, and hummingbirds.

It was introduced to western cultivation in the 1870s. The Arnold Arboretum in Boston received Japanese Tree Lilac seeds from Japan in the 1870s and distributed plants to gardeners across North America, beginning the introduction that eventually made it one of the most planted small street trees in the northern United States and Canada. It has been in continuous cultivation in western gardens for over 150 years without losing its relevance.

The seed-grown trees bloom in colors ranging from pure white to very pale cream. The flowers of Japanese Tree Lilac are consistently lighter than common lilac, ranging from pure white to warm cream or very pale yellow-white. Seed-grown specimens show subtle variation in the warmth of the cream tone and in the density and size of the flower panicles.

Growing Details

• Botanical Name: Syringa reticulata
• Stratification: Required, 60 to 90 days cold stratification
• USDA Zones: 3 to 7
• Soil: Well-drained, neutral to slightly alkaline, adaptable to a range of conditions
• Light: Full sun
• Height: 20 to 30 feet
• Spread: 15 to 25 feet
• Growth Rate: Moderate, 1 to 1.5 feet per year

Plant it where you want a flowering tree in June. There is almost nothing else that blooms at that moment with this combination of size, fragrance, and cold hardiness.