I have had spider mites in my garden for just over a year now, maybe 2, I have not given up on more than a plant or 2, at this point I have no webbing whatsoever. I buy beneficial insects every other week.
I find it funny how people freak the fuck out when they see pest in the garden. be proactive, don't spray anything else than water, have fun, it's gardening. you should be worried only if you see no pests, means your benes are either starving or not there either.
The very first thing to do when you see pest in the garden is to spray water to knock them off...