How to Prune begonia Pendula Group?
No pruning required

begonia Pendula Group · Begonia (Pendula Group)
In spring plant tubers, hollow side uppermost, in free-draining compost at 16-18°C. Plant out after the last frosts in fertile, humus-rich, moist but well-drained soil in sun or partial shade. Lift the tubers in autumn before the first frosts and dry off. See begonias: outdoors for further information
No pruning required