6" to 12"
It is a large deciduous shrub or multi-stemmed small tree, producing secondary shoots ("suckers") with stem diameters of up to 20 cm from the base or roots, which in the course of decades may produce a small clonal thicket.
Potential disease pests include several types of leaf sports and blights; insect pests include lilac borer, caterpillars, scales and leaf miners. Extract from Syringa species are toxic to various insect pests. A powdery mildew called Erysiphe syringae can also form.
Common Lilac is a very common ornamental plant in gardens and parks, because of the attractive, sweet smell of its flowers.