So, to plant the potatoes in a bag I used some Scotts Premium Topsoil. It is a bit tough to read in the picture, but the description says, “Consistent texture, no rocks or sticks…”.
I’m not sure exactly what the official size and weight of an object to be a rock or stick, but as you can see in the two pictures below, the fact that I got both of these from the same bag certainly caught my attention. Checking Wikipedia (link) I didn’t see any reference to any particular size requirement. I guess, one man’s stick could be another man’s twig. I guess as long as my potatoes grow well, I shouldn’t have too much to complain about.