Castor bean plants produce massive 3-foot-long leaves and colorful blossoms, making the plant popular for ornamental landscaping purposes. Even the seed pods can be decorative, thanks to their red or pink color and prickly appearance. Instead of getting castor bean seedlings in a nursery, pick the seeds from an existing castor bean shrub for future planting. Such propagation is often more economical than buying a started shrub.
Wait for the castor bean plant to produce seed pods, which have a round appearance, spiky growths along their exterior and measure approximately 1 inch long. Seed pods typically begin appearing in the late spring and early summer and become mature in the middle of summer, according to Palomar Community College.
Cut off the seed pod once it begins to take on a brown hue. Seed pods that are left to mature completely on the castor bean plant will burst open unexpectedly to spread the seeds inside, making seed collection difficult.
Place the seed pods in a tray, and put the tray in a sunny location to allow the seed pods to dry completely. They will crack open with a popping sound once they're fully dry.
Remove the three seeds found in each pod. The seeds typically measure 1/2 inch long and have a brown or black appearance with white or brown specks and stripes.
Remove any attached pieces of hull or plant flesh stuck to the seeds, according to Purdue University. Store the seeds in a resealable container until you're ready to plant them.