Lilacs are an easy to grow plant. They need at least 6 hours of sun a day to bloom well, and prefer sun all day long in the hottest spot in your garden. They are tolerant of a range of soil types.
Deadheading directly after they bloom will stimulate better flowering the following year. If you don’t deadhead, they only blossom extravagantly every second year. To keep the bush tidy trim out old branches and suckers from ground level. The bush propagates primarily through ground suckers and can become a wide shrub if not maintained yearly. To prevent powdery mildew you must increase air circulation through the plant. Prune out some of the older stems in the middle of the shrub after it has finished blooming to open it up.