Fiqh-us-Sunnah Volume 1, Purification and Prayer, Fiqh 1.059.

Section : Ghusl for women.

A woman performs ghusl just as a man does, except that if she has plaited hair she does not have to undo it, provided that the water can reach the roots of her hair. Umm Salamah said, “O Messenger of Allah, I am a woman who has closely plaited hair on my head. Do I have to undo them for ghusl after sexual intercourse?” He said, “No, it is enough for you to throw three handfuls of water on your head and then pour water over yourself. After doing this, you shall be cleansed.” (Related by Ahmad, Muslim and at-Tirmizhi, who called it hassan sahih.) ‘Ubaid ibn ‘Umair reported that ‘Aishah discovered that ‘Abdullah ibn ‘Amr was ordering the women to undo their plaits of hair (for ghusl). She observed, “It is amazing that Ibn ‘Amr orders the women to undo the plaits of hair for ghusl. Why doesn’t he just order them to shave their heads? I and the Messenger of Allah used to bathe from one vessel, and all I did was pour three handfuls of  water over my head.”(Related by Ahmad and Muslim.)

It is preferable for a woman performing ghusl to cleanse herself from menstruation or post-childbirth bleeding to take some cotton smeared with musk or perfume and wipe it over the traces of blood. This will remove the bad smell of the menstrual blood. ‘Aishah reported, “‘Asma bint Yazid asked the Messenger of Allah about ghusl after menstruation has ended. He said, “She should use water mixed with the leaves of the lote-tree and cleanse herself. Then she should pour water over her head and rub it well till it reaches the roots of the hair, after which she should pour water over it. Afterwards, she should take a piece of cotton smeared with musk and cleanse herself with it.” ‘Asma asked, “How should she cleanse herself with it?” He said, “Praise be to Allah, she should cleanse herself with it.” ‘Aishah said in a subdued tone that she should apply it to the traces of blood. ‘Asma then asked about bathing after sexual intercourse. He said, “She should take water and cleanse herself or complete the ablution, pour water on her head and rub it till it reaches the roots of her hair, and then she should pour water over herself.” ‘Aishah observed, “How good are the women of the ‘helpers’ that shyness does not keep them from learning their religion.” (Related by “the group,” except at-Tirmizhi.)