They can go outside in the borders/pots now it's summer. They are hardy, but some varieties more than others. If they are still under cover then give them a couple of days of inside at night, putting outside in day until they are used to the temperature change- hardening off. Decent compost, a John Innes type 2 or 3 would be fine if keeping them outside in pots.
Deadhead the flowers as the season goes on, & they should repeat flower until the frosts come.
They may not come through next winter, so it's a good idea to take cuttings off them in late July/August & then overwinter those under cover ready for next year.
Any that do come through next winter outside in borders dont need cutting back until late March/April, depending on whereabouts in UK you are, although I do tend to do mine earlier than advised & they cope- am in NWest. J.