Answer: Potentilla shrubs are cut back quite hard in the early spring. This tidies them up to remove winter damage and encourages dense regrowth with heavy flowering. After the main flowering period, you can shear them or lightly trim them back again to encourage rebloom later in the summer. It is too late in the season to trim them now, that would encourage late season growth that will not have time to harden off before winter and can result in excessive winter damage to the plant. I would suggest waiting until spring.
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