It has only been five days, but I sprayed all the tips of my plumeria (inside the solarium) with the coffee-solution. A few of the tips had evidence of spider mites. So far the young plumeria leaves look great and the spiders haven't woven any webs. Thus, not only does the coffee appear to be gentle on leaves (plumeria leaves can be very sensitive to insecticides and miticides) but may even be effective on mites.
Holy cow! No sign of fungus gnats in the soils either.
