Ghusl for women after junub

Is it necessary for a women to wash her hair as part of Ghusl when in state of junub? This seem to be confusion as it does make them lazy not to spend private time with their husband because of Ghusl and excuse could be that if hair are not washed each time the Ghusl is incomplete. What does hadith narrates when it comes to invitation to wife and she refuses because of having Ghusl or washing hair everyday which makes them week.