Pruning Spring Flowering Shrubs
Late spring is the time to bring overgrown lilacs, forsythia and other spring blooming shrubs down to size.
Prune spring blooming shrubs right after flowering to control their size without sacrificing next spring’s bloom. Lilacs, forsythia, bridal wreath spirea and other spring bloomers set their flower buds in summer. Pruning after this in late summer, fall or winter will remove the flower buds and all important spring floral display.
Prune a few of the larger stems right back to ground level. Reduce the height on the remaining stems as needed. Repeat this for several years and you will soon have green leaves from the ground to the tip of each branch and beautiful flowers to enjoy.
Consider waiting until late winter for major pruning jobs. You will be sacrificing the flowers, but the plants are better able to tolerate the stress of severe pruning and will recover more quickly at that time of the year. Just save a few of the trimmings to force into flower indoors.
A bit more information: Summer blooming shrubs like potentilla, summer blooming spireas, and blue mist spirea (Caryopteris) can be pruned in late winter or early spring before growth begins. Smooth hydrangeas like Hills of Snow and Annabelle (Hydrangea arborescens) and panicled hydrageas (Hydrangea paniculata) can also be pruned at that time. Wait to prune the bigleaf hydrangeas (Hydrangea macrophylla) as they bloom on old wood. Remove only deadwood and wait for the floral display.