I too have very sandy soil here in Florida, USA. My solution for a herb spiral in sandy soil is to take a negative--a medium sized tree stump sitting right in the middle of my garden area, about two feet tall, and build a small herb spiral around and over it, hoping the tree stump will anchor the herb spiral. Don't have many rocks here either, so will probably use some large fallen tree branches I have lying around to create the edges of the herb spiral until I can find something more permanent--I have an old pick up truck and tend to toss any rocks I find along the way into the back of the pickup. I already have rosemary, sage, and thyme growing in pots and ready to plant once this is built. We get 60 inches of rain, mainly in the summer, and are subject to the occasional hurricane with phenomenal amounts of rain all at once, so it will be interesting to see if this will work, or just all wash away. I plan to document it with my digital camera. This is probably a project for the Fall of 2003, as it's getting too late to plant much due to the summer heat.
NorthCentral Florida, USA. Mild coastal climate, rarely frosts.
60 inches of rain a year.
Two garden seasons, Spring & Fall. USDA Zone 8b
Spring dryest time, Summers wet, hot and humid.
Subject to occasional fierce storms, even hurricanes.
Elevation 42 feet. About 29-1/2 Latitude North