We like to grow all kinds of things just for the fun of it. This year we grew Castor beans. The plants are "huge" like at least 15 feet. We planted a row of about 35 plants. They are beautiful but, now it is fall and we need to pull them up. Since they are toxic to animals and children, how do we safely dispose of them . We intend to just take them to the landfill, but is that safe? Thanks for your help.