Hetty, I'm not sure if it's coral, it might be... my husband thinks it's limestone. At any rate, aside from the sparse grass on top, there's not much soil.
Yes, sand would be much easier. I remember back in my native PR, my grandmother could grow anything in her sandy soil; she lived by the beach. She had an amazing green thumb, and was very familiar with herbs for medicinal purposes. I didn't inherit much of her talent, unfortunately. It's been more of a learning experience for me, than a natural talent.
And Mike, I wouldn't mind 'sharing' cuttings with neighbors as long as they don't mess up the little tree.
At any rate, they'll be in my backyard for a good while before transplant to the front.