How often should a 13 year old girl wash her hair?

The updated, wise-guy answer is this: A 13 year-old girl should wash her hair as often as her parents say.

The original answer, with spelling corrections, is this: Well, it utterly depends on her hair type: some people have thicker, drier hair than others, some have much finer hair that develops oil much faster and easier. In order to give one's hair a healthy look it is vital that one washes and conditions it on a weekly basis, minimum.

Many say that in order to give your hair that perfect frizz or shine you need to wash your hair at least once every two days or even every day, though what people seem to forget is that the more you wash your hair, the drier it gets. In all honesty, a girl should only have to wash her hair a maximum of twice a week. If one has thicker, drier hair, once a week will do you just fine (because your hair is already thick, dry and full of volume, you don't need it any drier),

If you have finer, more oily hair, twice a week would be more practical. If you wash your hair a 1-2 times per week, you are guaranteed silky results (though most people are under the impression that the more you wash your hair the silker and shiner it gets). Trust me, this is only the case if you wash it only these amounts of times per week, sometimes less is better...