It is narrated from Sayyiduna Anas (may Allah be pleased with him) that the Messenger of Allah (peace and blessings be upon him) said: "When a woman performs the ritual bath (ghusl) after her menstruation, she should undo her hair and wash it with marshmallow (khatmi) and potash (ushnan); and when she performs the ritual bath after major ritual impurity (janabah), she should pour water over her head and wring it out."
Hadith Referenceالمعجم الكبير للطبراني / باب الألف / 751