My parents brought home a hibiscus graft for me from Hawaii in November. It is grafted on to a small piece of wood about 3 inches long. There were no instructions on the package but I put it in a pot, keeping the growth going in an upward direction right above the soil level. The growth is still green, but it's not growing and I don't see how it's rooting at all. What don't I know about how to do this right?