If you're looking to stockpile ricin, here's what you put in your garden, your very large garden.
The one in this picture grows by the fence at the local arb. It's rather petite, mainly because it's eeking out an existence under very difficult circumstances. Till the soil. Add some fertilizer. Water on occasion. It'll grow 15 or more feet high. Those leaves will be two feet wide, if not wider.
While the children were small and prone to eat whatever they found, I kept the castor beans out of sight. Later with the doods older, I put a few in the garden. We used it as a teaching tool. They examined the seeds. They knew that a single one would kill them. They marveled that the bugs could eat the bean and survive.
One grew at the edge of the drive next to the neighbor's yard. The local world marveled at it's lush tropical foliage. Then came the October Blow, as Cousin Lulu called the hurricanes. The castor bean fell directly into the neighbor's yard, and yes, being ever the typical suburban dweller, she was on my porch telling me as the sun rose that morning.
I hate suburbs. (I moved the castor bean a few days later.)