How to Build an Herb Spiral Part 1
Herb spirals are synonymous with permaculture. Most people even vaguely familiar with permaculture have encountered the famous herb spiral. The idea is to create a structure, the spiral that will have many different types of microclimates in a small easily harvestable area that looks beautiful. Herb spirals are meant to be very close to your kitchen, so you can easily go outside and pick a few fresh herbs while you are cooking. I like the idea because it adds function, beauty, and texture to the garden.
In research for this project, I came across many poorly constructed herb spirals. I saw dry laid bricks, with just straw placed behind the wall. I can’t imagine loose straw is going to support the wall very well. I saw simply a pile of soil with rocks just placed around it. I saw people planting mint, and other invasive herbs. It defeats the purpose of having the herb diversity if you plant herbs that will out compete the others. So I wanted to build something that looks nice, is functional, and is durable.
I used to have an employee named Marvin, who I would consider not a landscaper, but a landscape artist. He is the master of stacked stone walls. I would have liked to borrow his expertise for a day or so, as building a stone wall is a new skill for me. I did pick up a few things from working with excellent craftsmen such as Marvin.
Building an Herb Spiral, Step by Step
1. Measure and mark out your area for building the spiral. I picked a center point that was logical for where I wanted to put the spiral. I measured 3 feet out from the center point around giving me a perfect circle that was 6 feet wide. I planned to put my stone on the outside of my measurement so the planting space would not be infringed, because I planned to use relatively wide stone.
2. I dug out all of the topsoil and mulch down to hard pack. This is important as you don’t want your wall settling too much. I placed the soil on a tarp on my sidewalk to be added back to the spiral after construction.
3. I leveled the area. I did this the old fashioned way with a shovel, pick, hand tamper, and carpenters level. I had a couple of areas that I had to step up otherwise I would have still been digging. This part is really important. If your site is not level, the wall will not be sturdy.
4. I repainted and measured the spiral.
5. I separated my stone by thickness in ½ inch increments starting at 1 inch thick stone all the way up to 4 inch thick stones. I also made a pile of the scrap stone to be used to level stones and shore up spaces behind the wall. My plan was to use the thinnest stone first as I start the spiral, finishing with the thickest stone at the end of the spiral where the wall is the tallest. I tried to use the widest stone as the base.
6. Try not to have any vertical seams in your wall. You can avoid this by overlapping stones on the seams with each course. This is definitely easier if you have like thickness stones with each course. Make sure your stones are level and not wobbly. If the stones wobble, you can use a small thin stone placed strategically underneath to level.
7. Use your scrap stones to fill in any gaps in your wall to prevent soil from spilling out.
8. I did not do this, but some people put gravel at the base of the wall to improve drainage.
9. Fill in the spiral with good compost for your herbs to grow in. It is best to over fill the spiral as the compost will settle in time.
10. Blow or sweep off the stones to give a nice appearance. The herb spiral is now ready to plant.