A Japanese tree lilac blooms from late spring into early summer, a little later than the common shrub lilacs, often after their flowers have faded. Its large clusters of small, creamy white, fragrant flowers stand 6 to 12 inches high and cover the tree for a couple of weeks.

Why does pruning time matter for a Japanese tree lilac's flowers?

Because next year's flower buds form the summer before. Like other lilacs, the tree sets those buds on the current season's growth soon after it finishes blooming, so any branch removed between midsummer and spring takes its flowers with it.

When should a Japanese tree lilac be pruned?

Right after the flowers fade in early summer. Pruning then removes spent clusters and shapes the tree before new buds form, while late winter cuts are best kept to dead, damaged, or crossing branches.

What can keep a Japanese tree lilac from blooming?

Too little sun, pruning at the wrong time, or a tree that is still young. The tree needs about 6 hours of direct sun a day to flower well, cuts made after midsummer remove the coming year's buds, and a young tree may need a few years in the ground before it blooms heavily.

Frequently Asked Questions

Are Japanese tree lilac flowers fragrant?

Yes. The flowers carry a strong fragrance.

What follows the flowers?

Small capsules. Each one later splits in two to release a pair of winged seeds.

How long does a Japanese tree lilac grown from seed take to bloom?

Several years. Seedlings raised from Japanese Tree Lilac Seeds, a packet of 40 hand sorted seeds, spend their first years building size before they flower.

Does bloom time vary from year to year?

Somewhat. A warm spring can bring flowers a week or more earlier, while a cool one holds them back.