Rhodanthemum 'Casablanca' (Atlas Daisy Series)

hi!could I ask you some help? I have this plant too, first flowers are gone and I've cut them, but now some blossoms are dried before opening... do you have any idea about the problem? thank you so much!

I've checked the plant label and it says can survive on very little water and down to -5c but perhaps you need to give it a general purpose fertiliser.

thank you so much! Now there are two new flowers, maybe I gave her too much water and also now is a bit cold.. so I hope she will survive! :)