You can also plant the perimeter of your garden with Castor Bean Plants, that can easily grow 12' tall and 4' in diameter. Many Seed Catalogs list them. Start the seedlings indoors in late winter and plant them outdoors after all danger of frost.

The entire plant is mildly toxic. But the large Brown Beans are Highly Toxic-to-small-Children, pets and livestock; especially Horses. It contains the water-soluble toxin, Ricin. The roots are thought to permeate the soil with their mild toxin which Moles dislike. To keep the plants in bounds, remove the flower buds to prevent production of seeds.