Neem is natural and should cause no harm. A day or two after you kill'em all, spray plants down with h20 for rinse. Keep an eye out for new infestations. Easy to stop when you get them early. The eggs on the underside of leaves take a couple of days to hatch, so treat more than once.

Keep a clean grow area by spraying surface with 5-10% bleach. You can also use a product called Tanglefoot that will act as a barrier.

Do the mites come in from outdoors, or are you bringing in infected clones?

You will be happy with Neem.