When to prune trees & bushes
Never prune pine trees in the summer. Always prune when they are dormant between December and April for two reasons:
So they will not drip sap on your hardscape or patio furniture.
So they will not attract beetles — because beetles are not active during that time.
Always prune oak trees during their dormant season, June to September. It is best during the hottest days of summer to avoid attracting fungus.
Azalea, viburnum and some hydrangea bloom on old wood so always prune them right after their bloom time in the spring. Before you prune be sure to research if the shrub blooms on old wood or new wood.