Castor beans grow to a height of up to 15 feet and are prized for their lush, multi-lobed foliage and bright flowers. Start the plant from seeds harvested from an existing plant or purchased from a specialty garden store. Though the plant is very low maintenance, basic care strategies can ensure a successful start to your castor bean crop.
Prepare the planting site. Use a spade to break up the soil to a depth of 6 inches. Amend the soil with 4 inches of compost, mixed thoroughly into the dirt.
Water the planting site to moisten the soil to a depth of 3 to 4 inches.
Plant the castor bean seeds approximately 1 inch below the soil surface. If you're growing more than one plant, space seeds apart by 1 foot and separate the rows by approximately 3 to 4 feet, according to Purdue University.
Water the planting site twice daily or as necessary to keep the top 2 inches of dirt moist. The seeds will usually germinate within three weeks. After germination, reduce watering to once every three to four days, using enough irrigation to moisten the dirt to a depth of 8 to 12 inches.
Control weeds around the castor bean plant. The plants are susceptible to weed invasions because they grow relatively slowly and are comprised of a single tall stalk rather than dense, spreading undergrowth. Manually remove weeds for the first month of growth. Once the plants are 5 inches tall or higher, spread 2 to 3 inches of mulch on the planting site to keep weeds out.
Cut off the plant's blossoms once they wilt. This prevents the blossoms from developing castor bean seeds, which are extremely poisonous.