Senetti and potentilla advice

Hi everyone, me & the misses were at B&Q and picked up 3 senetti as they were a pound only they needed some pruning of dead branches etc but there's not much description about them on the care label, are they a perennial? Do I cut them down to the deck in winter or spring? As don't know what to do with them after some tidying up pruning of the plants as were in a state they have produced a few more flowers since planting, just need some advice on their care etc, also wondering how to take potentilla cuttings we have one newly planted this year red robin potentilla and when to do it as want about 10 in back garden around decking so would prefer to grow my own from cuttings rather than spend a tenner each plant. Thank you everyone. Sam