I only do the submerging in the fall & never thought about gnats or their larva at that time. I've only recently become aware of fungus gnats.As far as to how long.I just wait until bubbles appear at the top of pots.I do it in the yard.It takes a big container to submerge my hibiscus in.It works great for aphids.It helps with white flies but to be completely successful plants probably need more than 1 dunking.I didn't dream this up.I read about it on 1 of these forums.
sNs
