The best time to plant a Japanese lilac tree is in the late winter or early spring. Late fall is also an acceptable planting time. The lilac is small enough to grow near a deck or patio and lacks an aggressive root system, which means it’s safe to plant near patios, walkways, driveways, and septic lines.
Light
You will be most happy with a Japanese lilac tree if you grow it in full sun. It will survive if grown in partial sun, but it won’t produce as many flowers.
Soil
Since it needs well-drained soil, mix compost into the ground when you plant Japanese lilac trees. The compost will loosen the soil, promoting proper moisture flow. This is particularly important in clay-rich soils.
Water
Keep the ground evenly moist, but make sure it drains well. Mulch will help with water retention. So will compost. Suitable water retention means you won’t have to water the plant as often.
Fertilizer
While a Japanese lilac tree can live in soil of average fertility, it does better in more fertile soil. Feed the plant by mixing soil amendments into the ground every spring. Buy a balanced fertilizer if you feel an extra boost is needed. Make sure to follow instructions on the bag carefully since over-feeding can burn the plant. After applying the fertilizer every spring, hose down the soil so that the fertilizer goes down to the roots.
Types of Japanese Lilac Tree
Tree-form lilacs come in three subspecies, having subtle differences from one another (such as the Chinese being a bit smaller, etc.):
Japanese lilac tree (Syringa reticulata subsp. reticulata)Chinese lilac tree (Syringa reticulata subsp. pekinensis)Amur lilac tree (Syringa reticulata subsp. amurensis)
Cultivars are also available. The cultivars generally bear more blooms than the species plant and, for this reason, may be preferred over the latter. Cultivars include:
‘Summer Snow’: A smaller tree (20 feet high), this plant is even more tolerant of pollution than the species plant, making it an excellent street tree. ‘Chantilly Lace’: This is one of a few choices available with variegated foliage. In this case, the leaves bear creamy yellow margins. It grows to 20 to 30 feet high and 15 to 25 feet wide. Partial sun is better for this type. ‘Ivory Silk’: This is the most popular cultivar. At a maximum height of 25 feet, it stays a little shorter than the species plant. It begins blooming at an early age, and it bears many panicles. ‘Signature’: Gardeners truly interested in a continual sequence of blooms love ‘Signature’ because its panicles, although smaller than those on ‘Ivory Silk,’ come out a week or two later. Grow both to extend the bloom period. ‘Ivory Pillar’: This Japanese tree lilac sports a columnar form (25 feet high and 15 feet wide).
Comparison of Tree Lilacs and Common Lilacs
While common lilac shrubs and Japanese lilac trees belong to the same genus (Syringa), there are important differences between them, beyond the fact that you can more easily train the latter into tree form.
Flower scent: Common lilacs have one of the plant world’s most fragrant blooms, but many people feel that tree lilacs have flowers that smell overly sweet. The smell is often compared to the pungent smell of the flowers of privet shrubs (Ligustrum). Bloom time: A Japanese lilac tree flowers a bit later, giving you color in early summer (rather than late spring). This fact is useful as you plan out the sequence of blooms in your garden. Bark: The Japanese lilac tree’s bark is a pretty brown, studded with lighter lines (called “lenticels”), as on cherry trees, whereas the common lilac’s bark is an uninspiring gray.
Pruning
Perform maintenance pruning on a Japanese lilac tree as you would on any tree or shrub. This means removing damaged, dead, and diseased limbs as soon as you find them, thereby reducing the chances that your plant will experience severe pest or disease infestations. Also, occasionally prune out some of the limbs from within the canopy of mature trees to improve air circulation. Focus on removing any branches that are crossing and/or rubbing against each other. Beyond this maintenance pruning, Syringa reticulata often needs help in achieving the classic tree form. If left to its own devices, it will sometimes become multi-branched, rather than growing with a single trunk. To this end, prune off low branches each year in early spring until you expose as much trunk as you desire. Such pruning is especially important in the early years when you are training your plant to become a tree.
Propagating a Japanese Lilac Tree
Japanese lilac trees can be propagated from cuttings taken in the late spring or early summer. Once the cutting is planted in the soil, it should take root in about six weeks. Here’s how:
How to Get Japanese Lilac Trees to Bloom
These trees love to show off their fragrant flowers in the late spring and early summer. To get the most blooms from the Japanese lilac tree, plant in full sun and do a maintenance pruning. The flowers will last about two weeks and then produce green-colored clusters, which turn into yellow seed capsules that last during the cool months. Songbirds enjoy feasting on the seed capsules.
