All i gotta say is i can't believe you even thought about using it. Who ever told you that should be slapped very hard if not just severly beaten. Not only is the co2 so cold and it would harm your plants but its not the only thing thats cold many other flame retardants are in most fire extiguishers not only would you kill your plants but if your growing indoors in a small room with out good ventalation you'd probably kill yourself too. Just dear god please think about things before you try them if you put any thought into it you might relize how stupid it is before you even have to ask.