The proper time to prune deciduous shrubs (those that lose the their leaves each winter) is based on when they flower. Deciduous shrubs are placed into three groups:
- Those that flower in the spring on wood produced last year
- Those that flower later in the year on current seasons' growth
- Those that produce flowers, but flower are of little ornamental value
Shrubs that flower in the spring should not be pruned until immediately after flowering. Though pruning earlier will not harm the health of the plant, the flowering display will be reduced. Examples include forsythia, lilac and mock orange.
Shrubs that bloom on current seasons' growth or that do not produce ornamental flowers are best pruned in late winter to early spring. Examples include Rose-of-Sharon and some spirea.