Sounds like the selection called 'Zanzibarensis' is what you grew. Plain green, but MUCH taller & bigger growing than most other castor beans. When I grew them they reached at least 15 feet tall in a single growing season.

The dark-leafed varieties all seem to be selected for smaller size but try 'Impala', which has very nice foliage and can make it to about 10 feet or more with plenty of water and fertilizer. Also, for best growth start the seeds directly in the ground. The seedlings send out a very long taproot almost immediately upon germination and starting them in pots nearly always stunts them.

I dug up a photo of the 'Impala' I grew several years ago. This photo was taken in August 2003 and the brick wall is about 4 feet high. These are only about half the size of 'Zanzibarensis' but I like this cultivar because the foliage color is more subtle than many of the dark-leafed ones, and it grows relatively large. I haven't grown this one in several years but after looking back at this photo I'm inspired to try it again!

Fantastic picture. I need to remember to get more shots of the garden. The 'Impala' looks just like what I had last year. I saved some seeds and will plant it again this year. Also ordered some 'Zanzibarensis' seeds, and am considering the 'New Zealand Purple' or 'sanguineus'.

I believe that jungleseeds.com has a new variety which is supposed to be infused with more red colouration and approximates the size of the Zanzibarensis. I've not tried it yet, but it might be worth it as an experiment this summer.

is there a way to stop castor bean plants from getting too tall like cutting off the red flower which seems to be the next growth spurt