Hemp to Save our Planet!!! Hemp is not legal to grow in the US because big business wants it that way. Discovery Channel Planet Green star Shelley Pack exposes the truth behind the hemp conspiracy. Growing Hemp would clean up all the excess Carbon Dioxide in the air, replace all of our oil based products including fuel for our cars. Growing Hemp will also stop all the tearing down of trees for paper and lumber. Hemp can also make plastic, which is one of the worst burdens to the environment and our health.