I am going to assemble a garden shed in my back yard in a spot that is
presently occupied by three small trees. The trees are volunteers and about
6' high. Castorbeans I think. Here's my plan: Cut them down as low as
possible. Cover stumps with water softener salt (rock salt) and them upend
coffee cans over the stumps. The floor of the shed will cover the stumps
and I'm thinking that the salt and lack of sun will kill the stumps.

Will this work?