A. Lilacs produce buds for next year shortly after flowering. So if you wait too long, say until August or September, you will be removing buds for next spring, thereby reducing next year’s display. So timing is important. My advice is to prune as soon as your lilac has finished flowering. That will give it plenty of time to develop new flower buds. Q. When should I prune my spireas? A. That depends on the spirea. If it’s a spring flowering type (e.g. bridal wreath, Spirea prunifolia, S. nipponica), prune shortly after flowering. These types can become woody, leggy and less productive if not cared for properly. Remove dead and thin, weak growth first. Then remove up to one third of the oldest wood right down to the base. The other type is the summer flowering spirea, usually with coloured leaves (e.g. Goldmound, Goldflame, Mini Sunglo, Anthony Waterer series, etc; S. bumalda, S. japonica, and hybrids). Prune the bush hard in late fall or early spring, down to six inches, bef