"
"2 cubic foot hole".. is that meant to be 2'x2'x2'? (6cu/ft). THAT will grow a decent plant. 2 cubic foot is rather 'small' IMO, for outdoors. Roots will penetrate the hard pack clay, but it will restrict growth.
The larger the hole is that you dig, with proper amendmants, the better your plant will do. Nothing that you put in the dug hole, is going to loosen the clay outside of the hole. You need to dig it up and amend it.
I relize their are folks here with disabilities, or limits on the physical labor that they can perform. But IMO, if you're too lazy to dig a hole, you're probably too lazy to grow pot guerilla style.
NO OFFENSE intended..