How to Plant a Castor Bean


The castor bean plant's colorful foliage can make it a conversation-starting addition to your backyard. Its ability to reach 20 feet in height or more also makes it a potential privacy screen or windbreak. You can grow castor bean plants if you live in USDA hardiness zones 8a through 11. Though the plants can sometimes be sourced from a nursery, you can easily start the plant by sowing the actual castor bean seed.

Step 1

Prepare the castor bean seeds. Place the seeds in a dish and fill the dish with water. Soak the seeds for 24 hours.

Step 2

Ready the ground for planting while you're waiting for the seeds to finish soaking. Choose an area of your yard that receives direct sunlight for seven or more hours. Remove all surface vegetation and debris and break up the soil to a depth of 8 to 12 inches.

Step 3

Amend the soil. Add 1 to 2 inches of compost and thoroughly mix it into the soil. This boosts the soil's nutrient levels and also increases its organic content, which helps with moisture retention.

Step 4

Sow the castor bean seeds. Sink each seed an inch below the surface of the soil. If you're planting more than one castor bean seed, separate the seeds by 24 inches.

Step 5

Water the seeds twice daily to keep the soil moist. They will typically germinate within 14 days. Continue watering twice daily, as the plants thrive on lots of water.

Step 6

Add an inch of mulch around the base of the castor bean plant once it reaches a height of 3 to 5 inches. Mulch helps to conserve soil moisture.

Tips and Warnings

  • Castor bean seeds are extremely poisonous due to their high ricin content. Consuming castor beans can cause extreme abdominal pain and vomiting, and even death, according to Union County College. Cut off the plant's flowers to prevent seed growth, or keep all children and pets away from the plant.

Things You'll Need

  • Castor bean seeds
  • Container
  • Rake
  • Spade
  • Compost
  • Mulch


  • "American Horticultural Society A to Z Encyclopedia of Garden Plants"; Christopher Brickell; 2004
  • Union County College: Castor Bean Plant

Who Can Help

  • Farmers' Almanac: Average Frost Dates
Keywords: plant caster bean, grow caster bean, sow caster bean

About this Author

Josh Duvauchelle is an editor and journalist with more than 10 years' experience. His work has appeared in various magazines, including "Honolulu Magazine," which has more paid subscribers than any other magazine in Hawaii. He graduated with honors from Trinity Western University, holding a Bachelor of Arts in professional communications, and earned a certificate in applied leadership and public affairs from the Laurentian Leadership Centre.