Castor bean is a fast growing tropical plant, and it’s one of my favorite annuals. I love my red castor beans, they add a wonderful contrast of color and texture to my tropical garden. I get tons of compliments on them, and everyone asks what they are.
Every fall I collect the castor plant seed from my garden, and then plant them again in the spring. It can be a bit tricky to germinate castor bean seeds, but it’s well worth it to grow these gorgeous plants!
Growing Castor Beans From Seed
It’s true that castor plants (especially the red castor bean plant) are beautiful additions to the garden… but be careful with this one. Castor beans (all parts of the plant and it’s seeds) are poisonous if ingested. So you might not want to grow it in your garden if you have pets or kiddos running around.
Castor beans can be really easy to grow from seed, but they can sometimes be challenging too.
Where To Grow A Castor Plant
Castor bean plants need a full sun location and lots of heat to grow their best. They will tolerate shade, but the plant will stay small.
Choose a location in your garden where the castor bean plant will be protected from high winds. It’s best to grow castor plants in fertile soil that drains quickly. They like a lot of water, but they don’t like soggy soil.
You could grow them in a large pot, but their growth will be stunted. If you don’t know where to buy castor bean seeds, here is the type I grow… red castor bean seeds.
When To Plant Castor Bean Seeds
Castor bean plant seeds can be sown directly in the garden; but in areas with short growing seasons like mine, it’s best to start them indoors 4-6 weeks before last frost. Castor plant seeds are not a good candidate for winter sowing, they will only rot.
Castor bean plants can be challenging to grow from seed, but there are a few steps you can take to make it easy to germinate castor seeds.
How To Grow Castor Bean Plant From Seed
1. Soak castor bean seeds: The first step for successfully germinating castor plant seeds is to soak them in warm water before sowing. Soak castor seeds for about 24 hours before planting.
After soaking the seeds, it will look like one end has popped out – this is normal. To give your castor bean plant seeds even more of a boost, try soaking them in diluted organic fish emulsion, liquid kelp or compost tea.
2. Choose the right container: It’s a good idea to plant castor bean plant seeds in a deep container, unless you plan to transplant them shortly after they start to grow.
Once castor plant seeds have germinated, the seedlings grow very quickly. It only takes a few days for the seedlings to outgrow seed starting trays.
You could start castor bean seeds directly in plantable peat pots to make transplanting them to the garden a snap. If you prefer to use something more sustainable than peat, try coco coir or cow pots instead.
Otherwise, plastic seedling pots are perfect (and reusable).
How To Plant Castor Bean Seeds Step-By-Step
- Fill your container will a high quality seed starting medium, or you could use large peat pellets instead
- Drain the water from the seeds
- Make a hole in the dirt to the proper depth (castor bean seeds should be planted 1″ to 1 1/2″ deep) and drop a castor plant seed into the hole (It doesn’t matter which side is up, castor plant seedlings will find their way to the top)
- Bury each castor bean seed with soil and gently press it down, but don’t pack the soil tightly over them
- Cover the containers with plastic wrap or put them into a large plastic bin with the lid closed to keep the soil moist during germination
- Keep the soil evenly moist, but don’t allow it to get soggy. Soggy soil can cause castor bean seeds to rot
Germinating Castor Bean Seeds
It can take a long time to germinate castor bean seeds, so be patient. The typical germination rate for castor seeds is 10-21 days.
I’ve had castor plant seeds take as long as a month before finally sprouting, so don’t panic if it takes longer than what it says on the seed packets.
Castor beans need warm soil to germinate, so adding bottom heat using a seedling heat mat will help castor bean seeds germinate much faster, and lower the risk of seed rot.
Caring For Castor Bean Plant Seedlings
Castor plant seedling lighting – After castor bean plant seeds finally sprout, the seedlings grow very fast. As soon as you start to see the seedlings popping up, it’s time to add a grow light.
Since they grow so fast, a seedling grow light is a must for growing castor bean seedlings indoors to prevent them from growing weak and leggy.
Make sure the light hangs an inch or two above the seedlings at all times, and keep it on for 14-16 hours per day (use an outlet timer to make it easy to control the lights). Check a few times per day, and adjust the height of the light as the seedlings grow.
Related Post: A Beginner’s Guide To Grow Lights For Seedlings
Fertilizing castor bean plant seedlings – Once your castor bean plant seedlings grow their first set of true leaves, it’s time to start fertilizing them.
You could also buy compost tea bags and brew your own liquid compost fertilizer. Start with a weak half dose, and gradually increase it to full strength over time.
Learn more about how to care for seedlings here.
Planting Castor Bean Seedlings Into Your Garden
Before you can plant your castor bean seedlings into the garden, they must to be hardened off to get them ready for life outdoors.
Once that’s done, wait to transplant them in the garden after all chance of frost is gone and the soil has warmed up.
Castor bean plants hate the cold, so it’s best to wait to plant them than risk planting them too early. If the soil or weather is too cold for them, the seedlings could die or their growth could be stunted.
Castor bean plants are fun to grow, and they add gorgeous color and texture to the gardens. But remember, all parts of the castor bean plant, especially the seeds, are poisonous if ingested.
If you’re concerned about the toxicity of the seeds, you can cut off the flowers to prevent castor plant seed formation. Keep castor bean plant seeds out of reach of children and pets.
Next: Learn how to collect castor bean seeds from your garden plants so you can grow them year after year… How to Collect Castor Bean Seeds From The Garden
More Tips For Growing Seeds
- How To Make Your Own DIY Seed Starting Mix (With Recipe!)
- Tips For Growing Seeds Indoors For Beginners
- How To Test The Viability Of Seeds With An Easy Seed Germination Test
Share your tips for how to grow castor bean plant from seed in the comments section below.