In spring, some gardeners sharpen the pruners and eagerly start to tackle unruly plants. When it comes to certain flowering shrubs, though, waiting until the right time prevents making an untimely cut.
Take lilacs, for example. If you prune at the wrong time, you'll cut off the buds and will have to wait another year for blooms. Most spring-blooming shrubs bloom on "old wood" and are best pruned right after blooming. These include beauty bush (Kolkwitzia amabilis), deutzia, forsythia, quince (Chaenomeles spp.), mock orange (Philadelphis spp.), and lilac (Syringa spp.). Don't prune if the shrub is producing new buds, which usually occurs right after blooming. Do remove suckers, dead or broken stems, or branches that cross or rub, though.