The herb spiral is a permaculture gardening method that uses nature to its full potential. Gravity allows the water to seep through the levels meaning that the plants at the top get full drainage while the ones at the bottom may reside in a simple bog. It also gives your herbs shady spots with varying degrees. The herbs that need full-sun can be grown in those positions while more shade loving plants can be located on the opposite side.
What a great idea—and pretty. If I had a backyard, I'd definitely consider building one of these. (via gw)
Will and I created an herb spiral at our old house which while not as pretty as the one in your link, was a great way to have fresh herbs growing near the kitchen. We had oregano, thyme, chives, cilantro/coriander, spearmint, and sage. I kept trying to put basil and tarragon in the mix but they never did well here in Portland, OR. One thing I will say is that the plants got much bigger than I expected (they thrived). However, since I planted them too close together (per the directions I was working with) some of the plants tried to crowd each other out. So I would say if you try it make sure you pay strict attention to how much room the plants need. Cheers!
I am hoping to build a herb spiral today