Hi Tanta it depends on which ones you mean. If they are the out door ones then you don't need to do anything. if its the indoor ones then you can do one of 2 things. either remove the spent flowers and give them a general feed such as Baby bio . I keep mine in leaf all year with gentle watering.
or you can reduce the watering until all the leaves die back. then keep the pot in a cool dry environment and then in august start watering again. that way they will reflower from October/November.

welcome to GOY too.