How to Prune giant sowthistle?
No pruning needed

giant sowthistle · Sonchus fruticosus
Also known as: shrubby sonchus
Best grown in a container of free-draining, loam-based compost, standing outdoors in summer and overwintered in a frost-free position. However, if planted outdoors the roots will often survive even if the top growth is cut down by frost
No pruning needed