Is lilac a tree or a shrub? It all depends on the variety. Shrub lilacs and bush lilacs are short and compact. Tree lilacs are trickier. The classic definition of a tree is that it is over 13 feet tall and has a single trunk. Tree lilacs can grow up to 25 feet high and have a tree-like appearance, but their many stems tend to get them classified as bushes. They are not technically trees, but they get big enough that you can treat them as if they are.
Lilac Bush Varieties
Lilac shrub or bush varieties can be split into two categories: large upright and densely branched.
In the first category is the common lilac, a hugely diverse plant that comes in a wide range of colors and fragrances. This large upright shrub lilac usually grows to 8 feet in height, but some varieties can be as short as 4 feet.
Densely branched shrub and bush lilacs are specific types bred for lots of flowers in small space. The Manchurian lilac gets anywhere from 8 to 12 feet tall and wide, and grows in a very dense pattern that does not require yearly pruning and makes for showy flower displays. The Meyer lilac is another good densely branched choice.
Types of Lilac Trees
There are a few types of lilac trees that offer the fragrance and beauty of the lilac bush varieties, with the addition of height and shade.
- The Japanese tree lilac reaches heights of 25 feet and produces fragrant white flowers. A very popular cultivar of this variety is the “Ivory Silk.”
- The Pekin tree lilac (also called the Peking tree lilac) can reach 15 to 24 feet and comes in a variety of colors from yellow on the Beijing Gold cultivar to white on the China Snow cultivar.
It is also possible to prune the common shrub lilac’s many stems down to a single trunk to emulate the look of a tree.