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...
It depends on their hair. If you have super curly hair you should wash it every other day... maybe every 3 days. If you have greasy hair then wash it everyday. If you have straight hair just wash it everyday. Mostly every girl washes her hair everyday.
How often you should wash your hair in a cold climate depends on your hair's natural greasiness and how comfortable you are with it. You should wash it whenever you feel like it is too greasy.
Women should wash their hair at least every two days. But I wash my hair everyday.
You should wash your hair every other day or less if the hair is thinning.
You should wash your hair every week if you have thick hair and you don't always put oils in your hair. UNLESS you have thin hair. You should wash your hair hair every other day!
Although I wash my hair everyday, it is said to wash your hair every other day in order to keep the natural oils and not dry out your hair.
Every other day should be enough
Models wash their hair often, depending on the work they do.
American girl hair should not get wet except for a slight mist to help with styling.
A person should not wash their hair too often because it does increase the rate of oil production. Ideally, folks should wash their hair no more than two or three times per week.
2-3 times a week
weekly at least.when you feel the need.