Are Your Darks Dark Enough?

"Red Onion"

Oil on Canvas, 6" sp., c. Catherine Vines

   

I seem to be having trouble getting my darks dark enough lately. In this case, I can see that darker shadows, especially at the base of the onion, would help settle it in space.

I also need to work on my backgrounds. I think they could be much richer and more interesting. SO much to learn and so little time.