Syringa reticulata Seeds | Japanese Tree Lilac
LATIN NAME: Syringa reticulata
COMMON NAME: Japanese Tree Lilac
Plant Profile
Japanese Tree Lilac is the one lilac that becomes a real tree. In the wild, on the edges of woods in Japan, Korea and the Russian Far East, it can reach twelve metres, though garden plants usually stop at six to eight. The bark is smooth and cherry-like, marked with horizontal pores, and it peels in thin strips on old trunks.
Flowering comes in late June, later than any other lilac, with dense, upright panicles of creamy white that smell of privet rather than of lilac. The leaves are larger and more pointed than those of the common lilac, and they turn a clean yellow in autumn. Ivory Silk is the cultivar most often planted as a street tree, and it is valued for a single straight trunk and for flowering at a young age.
Science & Biotechnology
The species was first described as a privet, Ligustrum reticulatum, by Carl Ludwig Blume in 1826 from Japanese material, and its transfer to Syringa came only in the twentieth century, once its capsule and seed had been properly compared. That history explains a good deal about the plant: the small, creamy flowers and the flattened capsule are closer to Ligustrum than to the fat, winged seed of Syringa vulgaris.
Molecular work places it with Syringa pekinensis, and some authors treat the two as subspecies of a single variable tree lilac. Cultivars are selected mainly for a straight trunk and for reliable June flowering; Ivory Silk was raised in a Canadian nursery in the 1970s and has since been planted in thousands of municipal schemes.
Uses & Benefits
Tree lilacs are planted where a small tree is wanted rather than a shrub: along streets, in parking islands, at the corner of a lawn. They take hard clipping, tolerate road salt and compacted ground better than most flowering trees, and they flower reliably in a cold climate. The scent is strong and travels, closer to privet than to lilac, and some people find it heavy in a closed room, so cut branches are best kept out of doors.
The wood is hard and close-grained, but the tree is too small to be worked commercially. In Japan the species is planted near temples, and its flowering is noted in garden diaries as the close of the lilac season. It is also one of the few lilacs that can be grown as a single-stemmed specimen without grafting, which is why it is used in formal plantings where a shrub would look out of place.
Growing from Seed
Sow in autumn and leave the pan outside through winter, or give the seed twelve weeks of cold at 2-4 °C in damp sand. Use a free-draining mix of two parts loam, one part leafmould and one part grit, and cover the seed with no more than five millimetres, since light helps germination.
Keep the pan in a cold frame and be patient: germination can take three months and often continues into a second year. Once the seedlings are up, give them light and air at once, because damping-off is the main risk in a closed frame. Pot them on each time the roots show at the drainage holes, and plant out in autumn, staking for the first two years. A tree lilac needs a single leader if it is to look like a tree, so rub out competing shoots in the first three summers.
Our Take
The latest lilac to flower and the only one that makes a proper small tree. Plant it for June scent and for cherry-like bark in winter.
Related Reading
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