Not necessary, once the plant is chopped and killed most of the mites will leave, they won't be giving you anymore problems. Although mites are usually gonna stick around and wait for the new crop, so make sure that you are using something next time in order to prevent and or keep there numbers down. For some it takes a few runs to completely eradicate mites. It can be a hard long fought battle, but using something all natural and safe throughout your run for mold and mites is always a great idea. A bit of preventative measure is gonna help you huge in the long run, check out Onyx spider mite and mold killer.