How to Grow and Care for Castor Bean

Castor bean plants have large, star-shaped leaves with vibrant red seeds, and they grow quickly, growing to a human height in a single summer. These bold plants stand out in the landscape, thriving in full sunlight, well-draining soil, and warm weather.

However, castor bean plants are very toxic to people and pets.

Castor Bean Care

Castor bean plants are typically grown during the summer in most environments and will quickly reach sprawling heights, making them an eye-catcher in your landscape or a great option for a living privacy fence if grown together.

Here are the main care requirements for growing a castor bean plant:

• Choose a spot that gets full sunlight, ideally at least six hours of direct sun per day.
• Prepare well-draining soil that holds some moisture.
• Water regularly, but do not let the plant sit in wet soil for long.
• Feed castor bean plants regularly with all-purpose fertilizer.

Light

Castor bean plants like full light and should be planted somewhere in your landscape where they get at least eight hours of sunlight a day. Avoid putting the plant below any towering trees, which can impact the amount of light it can get. Additionally, keep in mind that the more sunlight your plant gets, the fuller and more productive it will be.

Soil

Soil that is rich and moist will produce the best results for your castor bean plant. The mixture should be nutrient-dense and hold moisture well, but should not be boggy or easily waterlogged. If your intended planting zone isn't known for its soil, you can amend the mixture with some organic matter to increase the nutrient density.

Water

Castor bean plants like soil that is consistently moist, but you should take care not to overwater them. Generally, the plant likes around 1 inch of water per week, either from rainfall or manual watering. Keep in mind, that amount may need to increase if you experience drought-like conditions or are having an especially hot summer.

Temperature and Humidity

True to their tropical nature, castor bean plants like warm temperatures and above-average humidity levels. If planted in the right USDA hardiness zones, your plant should be more than happy. As a rule of thumb, castor bean plants need soil temperatures of 50 degrees Fahrenheit to 64 degrees Fahrenheit to be planted outside and will grow and thrive best in an environment that ranges from 68 degrees to 80 degrees Fahrenheit consistently.

Fertilizer

For best success, feed your castor bean plant once a month with a general, all-purpose fertilizer.

Types of Castor Bean

There are multiple types of castor bean that you can grow, offering different foliage colors and unique seed pod hues:

• R. communis 'Carmencita Bright Red' is red throughout, with red leaves, flowers, and seed pods.
• R. communis 'Carmencita Rose' conversely has blue-green leaves and seed pods that are a bit more orangey.
• R. communis 'Gibsonii' can grow up to five feet tall and has red leaves with pink seed pods.

Pruning

In most areas where castor bean plants are only grown in the summer, no pruning will be necessary. But if you live in USDA hardiness zones 9-11 and are growing castor bean as a perennial, you may want to prune it in spring to maintain a desired shape. If doing so, be sure to wear protective gear, such as goggles and gloves, to protect yourself from the plant's toxic sap.

How to Grow Castor Bean From Seed

Castor bean is most commonly propagated from seed, and once the seeds germinate, the plants grow quickly. Here's how to grow castor bean from seed:

1. Start by soaking the seeds overnight, which will speed up germination.
2. Sow the seeds about an inch deep.
3. Keep the soil warm and damp.
4. Remain patient until the seeds germinate, which can take a few weeks.
5. The seedlings will grow fast, so if you plan to transplant, do so promptly.

Common Pests

Fortunately, castor bean plants do not have a lot of issues with pests or with plant diseases. That said, spider mites have been known to attack stressed castor bean plants in times of drought. You can prevent this by keeping castor bean plants well-watered, especially during drought-like conditions.

How to Get Castor Bean to Bloom

While the flowers on the castor bean plant are insignificant, many growers are excited to see their castor bean plants flower for the colorful seed capsules that come next.

Bloom Months

Castor bean plants bloom in the summer and fall, from August to November.

What Do Castor Bean Flowers Look and Smell Like?

The flowers on castor bean plants are small and greenish-yellow, and they have a light, sweet scent. They pale in comparison to the bold red seed pods that follow.

How to Encourage More Blooms

Castor bean plants should flower easily. Make sure your plant is getting enough sunlight, water, and fertilizer.