Without checking, and you can google this on line, I am not so sure about full sun all day long. Maybe that is too much effectively burning the plants.
You have to keep the moisture up.
Edit after research.
They can take full sun but they do not like the heat. So the google reference I found said that when it gets warm they do better shaded from the strong sun between 10-2pm.
So I would suggest moving them where they get either morning or afternoon sun. The research said that they do well in the shade. Perhaps they will bloom with fewer flowers but they will still bloom.
Mine get less then two hours of sun in Michigan