Question: what are rhs pruning groups?
Answer: Pruning group 1: Light pruning. ... 
Pruning group 2: Early-flowering shrubs. ... 
Pruning group 3: Shrubs which shoot from the base. ... 
Pruning group 4: Summer-flowering shrubs (Hydrangea) ... 
Pruning group 5: Deciduous winter and early spring-flowering shrubs. ... 
Pruning group 6: Summer or autumn-flowering shrubs.