2-3 times weekly. As a rule of thumb, you are advised to wash your extensions a few times (after every 15-20 wears )in a month, depending on their conditions. However, stick to the 2-3 times regimen if you wear your extensions too often. Washing it fewer means build-up over time, while washing more than that leads to damage. Also, if you have curly hair extensions, washing them too much would destroy the curls, so it is best to clean them once a week.