This was our herb spiral the first year building it (you can see the process here-->
http://littlemountainhaven.com/how-to-build-a-herb-spiral/)
and here it is 3 years later all filled in + my review (see full pics here-->
http://littlemountainhaven.com/the-herb-spiral-3-years-later/)
I will be honest, the weed seeds that land in-between the rocks drive me nuts to weed out!! That might be because we have a crazy amount of weeds living on a mountainside but I'm not sure I'd build one again. Also keep in mind if you live in a super cold climate the snow doesn't always cover the top and causes more plant damage to the 'heat lovers' (I've replaced the top plants 3 times now). We've been getting a monsoon season every summer too and the intense rainfall has caused many rocks to shift downwards.
