When you have a spider mite infestation, you still have to take in account for where they came from. How would one get rid of mites on a heavily infested pepper or garlic plant? Yup you guessed it, not pepper or garlic. If your indoors i wouldnt even fuck with organic pesticides, your just giving them a chance to come back and lay more eggs, those eggs that hatch will not give a shit about the last used organic approach without drowning or saturating them with a high ppm organic solution (which is pretty much impossible without a dunk or fogger).