Again, when you dump your dirt on someone else's property without permission, this is illegal dumping and calls unnecessary attention to yourself, as well as being pointless when there are safer, easier, and LEGAL ways to do it. Growers get caught by committing other crimes in the process of growing- stealing electricity, unauthorized use of dumpsters, dealing. The local PD might be kinda bored and decide to give those trash bags to their lab to train the new technician how to take prints off plastic sheeting... uh oh, they match this local dude who has a prior for poss of class D... uh oh, the bag was full of used dirt... uh oh, there's a knock at your door... see where this is going?
One of the bonuses of the black garbage bag on the porch is that subjecting it to temperature extremes kills pests and makes it safe for use on your friend's veggie patch. He REALLY doesn't want your thrip infestation!
Growing a plant on a windowsill is just asking for trouble btw! Be careful!