I am having a problem with spider mites on my containers of Hibiscus plants( I have 12 of them). I have sprayed with Horticultural Oil x3 and it hasn't been effective. Has anyone tried buying Predatory Mites and do they work in container plants? What type of predator mites do you buy for a high humidity summer. I live in Houston. Thank you so much! I have battled this since last summer. I'm about to give up on hibiscus!