How long does fox farm happy frog soil stay good for when opened? Any recommendations for soil for autoflower?

as long as it doesn't get wet in the bag,you'll be fine and can keep it even longer.I remember using soil stored for a year.to be sure,you can open some little holes on the bag surface to make it breath.it must already have some on it.Not wet but a little moist it should be.for gnats, you can put the bag in the sun to dry.

I use Kryptonite soil. I have used it for Autos and Photo's... start to finish... just add water! Happy Growing!😁