Green-Moo, that sounds interesting! I've never seen a herb spiral. Yes, I could create a channel ok I think...it's just the amount of water that pours off that edge is from the whole hill might be too much for it. I'd need to figure out how deep it would need to be. I love the gravel idea with pots on top of it. I'll investigate herb spirals more, thanks very much for that idea!
Any suggestions on herbs suited to shade? It does get a bit of sun in the morning, maybe a couple of hours but once the trees fill in more that might not be the case.