I want to reuse 3 gallon fabric bags. Do I need to wash them before using them?
yes, even if you just wash them with the hose like a pressure sprayer. I wash all my bags after use, recycle the soil and get 3 or 4 grows per bag before they start falling apart. I spray with peroxide 3% and sometimes an alcohol spray too. I migrate some of my bags in and out so I do not want and hidden eggs / larvae / bacteria creating future issues