Your first job would be to decide if your flowering deciduous shrub needs pruning, You will need to step back and look at your shrub and determine what kind of look do you want.
Do you want a compact, bushier, one that produces more flowers, blooms longer, or a shrub that has a more natural shape? After you have decided that your shrub needs pruning you will have to think about timing. Usually your first thought would be after flowering. With deciduous flowering shrubs that is not always the case.
Prune Spring flower shrubs on old wood after the flower fade. This will allow the plant lots of time to develop flower buds on the stems that grow all summer after the old ones were trimmed back. Summer flowering shrubs such as butterfly bush and stewartia usually bloom on the current year’s wood, They are pruned in early spring, just before the shrub begins growing to produce lots of new growth for new flowers.
Use hand pruners for most of the cutting. A lopper will be handy for the thicker stems of mature shrubs. After planting the shrub it is best to wait 3 years to start pruning your shrub, unless there are diseased or dying stems. Prune only when it is needed as per one of the reasons we have mentioned above or leave the shrub to grow naturally. Do not prune more than 1/3 of the shrub at one time.
Summer-flowering shrubs that are pruned in early Spring:
Includes, Caragana, Deutzia, Forsythia, flowering almond, lilac, purple leaf, sand cherry, rhododendron, and Rose of Sharon
In the case of lilac and rhododendron, even if pruning for size is not required, at least remove the spent flowers and prevent the plant from setting seed. This will make the plant produce more flowers next year.
Summer flowering shrubs should be pruned in early spring before growth begins, then pruned again to remove spent flowers. These include roses, pink spireas, Potentilla, butterfly bush, Blue Mist shrub and hydrangea
When to Prune Other Deciduous Shrubs:
*Late Winter- Privet
*Early Spring- Burning Bush, Deciduous Holly, Japanese Barberry ,Smoke Bush, Staghorn Sumac, Spirea, and Potentilla
*Late Winter Early Spring- Cotoneater, Northern Bayberry
Remove, suckers in the summer (see list below) and remove diseased and dying stems at any time!
Deciduous Shrub that often produces Suckers:
Bottlebrush buckeye, Lilac, Northern Bayberry, Staghorn sumac and witch Hazel
Hope this article helps guide you on your way for pruning flowering deciduous shrubs !
Submitted by Marty Schwende
Lowe,Judy- “Pruning an illustrated Guide”-Cole Springs Press-2013
Jeff Cox-“Your Organic Garden”-A Rodale Garden Book-1994