crissy, sm's are very susceptable to cold. extremely... if temps are below freezing, you can kill the mites in ten to fifteen mins. i don't think it kills eggs, but it kills larval and adult stages.

doing so on a weekly basis could cause hermies in weak strains... keep this in mind. a hardy strain, esp a cold liking strain (ie nl) could probably take the abuse with no probs.

edit: leaving out for more than fifteen minutes can cause freeze burn to leaves and lengthy exposure will freeze stems and kill the plant. i don't recomend leaving out for more than ten but i've gone as long as fifteen with no probs (except slight classic stress symtoms, ie curl and wilt)