Have you ever heard of herb spirals? I saw one in Costa Rica once. I found it nice, but, after taking my permaculture course, I realized that it’s much more than that. Like many things in permaculture, it performs several functions at once. But what is a herb spiral? What is its purpose? How do you build it? This article will answer all of these questions and more.
What is a herb spiral?
The herb spiral is a gardening technique used in permaculture, which involves placing various aromatic herbs in a conical spiral. It allows you to have all your herbs on hand in a small space close to the kitchen. The goal is to be able to go out to pick your herbs wearing only slippers when you make a recipe, even when it rains. That’s close!
Why a spiral?
The spiral is a pattern that is often found in nature, and permaculture likes to get inspired by nature. Think of snail and shellfish shells, fern leaves, vine tendrils, Romanesco broccoli, animal horns, hurricanes, galaxies and even our DNA!
The purpose of the herb spiral is threefold:
Efficiency
The spiral is an extremely efficient pattern that wraps 25 feet of linear garden into a spiral 4 to 6 feet in diameter. We want to save steps by finding all of our herbs in one place.
Access
With its raised centre, the spiral facilitates access to the herbs in the middle. Indeed, it is sometimes difficult to reach plants 3 feet away without walking on the soil and compacting it, so a maximum width of 4 feet is usually recommended for gardens with access on both sides. For the spiral, we can go up to 6 feet in diameter thanks to its conical shape, which brings the middle closer to the hand of the picker.
Microclimates
The herb spiral cone creates different microclimates and it is important to consider this when planning where to plant the herbs. In the northern hemisphere, the north and east sides will be more shaded, while the south and west sides will be more exposed to the sun. The bottom of the spiral will have wetter soil, while the top will be better drained, especially if sand is mixed in. If the prevailing wind blows from the west, the east side of the spiral will be better sheltered. Of course, all of these microclimates depend on where you build your herb spiral and whether the presence of a tree or a building is affecting it.
How to build a herb spiral?
- Make a plan.
a. Plan the spiral location. It needs a sunny site, 4 to 6 feet in diameter with enough space to walk around it, located as close to the kitchen as possible to encourage the use of herbs.
b. Plan where to plant herbs in the spiral based on their needs and microclimates (sun/shade, dry/wet, windy/sheltered). Try alternating perennial and annual herbs to avoid having large empty holes in your spiral if you decide not to replant annual herbs the following year.
- Gather the materials required.
Materials
- cardboard to prevent weeds from growing
- pavers/stones to outline the cone
- gravel to facilitate drainage in the middle
- various organic matter (branches, leaves, food scraps, without weed seeds) to fill the middle of the cone and provide future nutrients for the plants
- compost/soil/sand to form a layer of at least 6 inches on the cone
- stones/logs/bricks/pavers/etc. to shape the spiral structure
- herbs (seedlings or seeds)
- mulch (straw, leaves, cedar)
Tools
- scissors to cut the cardboard
- bucket and string to draw the circle
- shovels (large and small) to transport gravel, soil and mulch, and plant herbs
- watering can or hose to wet cardboard and soil, and water herbs
- Prepare the site. You can build the spiral directly on your lawn, as long as you install a barrier to stop the grass from growing. A few layers of wet cardboard will do the trick. They will block access to sunlight and oxygen, and the grass will die before the cardboard breaks down. The decomposed organic matter (grass and cardboard) will then serve as nutrients for the spiral plants. It is also possible to build the spiral in an existing garden bed, in a kiddie pool, on your driveway, etc.
- Draw the circle. This can be done by placing a bucket or post in the middle of the circle. For a 6-foot-diameter circle, tie to the bucket a string measuring 3 feet long from the middle of the circle. With a pencil at the end of the string, draw the contour of the cone. Place stones/bricks/pavers around the cone to delineate the edge.
- Build the cone. Depending on the diameter of your spiral, the cone should be 2 to 3 feet high (half the diameter). A cone measuring 6 feet in diameter and 3 feet tall requires about 28 cubic feet of material
or 1 cubic yard. If you buy all that soil, it could be expensive.
a. Try using materials that you have at your disposal to fill the middle of the cone. In fact, it is a good idea to put gravel in the centre to provide some structure and enhance drainage from the top of the cone.
b. Cover the gravel with all kinds of organic matter (branches, leaves, food scraps, etc.) from the coarsest materials to the finest, avoiding all weed seeds. It’s a bit like building a compost pile. These materials will break down slowly and feed your herb spiral for years to come.
c. Cover the last six inches of the cone with good quality soil or compost. At the top of the spiral, mix sand into the soil to promote drainage for plants that prefer drier conditions (just think of Mediterranean herbs such as rosemary, oregano and thyme).
d. Wet your materials regularly because wet soil tends to collapse. - Define the spiral. Taking care not to walk on the soil to avoid compacting it, draw the shape of the spiral on the cone. Place large stones, bricks or pavers on your line to define the spiral and retain the soil a little.
- Plant the herbs. Following your plan, plant your herbs in the spiral. Leave enough space for them to thrive.
- Cover with mulch. This will prevent weeds, conserve moisture and protect the soil from erosion.
- Water regularly at the beginning. Like any seedlings, young herbs will need water to establish their roots. After a few weeks, you will be able to forget about the spiral, except in case of extreme drought or more delicate herbs.
What I did
I started by choosing the location for my herb spiral: at the end of a sunny, oval garden bed in the front yard, for everyone to see.
I then developed my plan using the Planter application:
As you can see, the plants that need more moisture are spread around the bottom of the spiral (mint, nasturtium, basil, chives). Mediterranean plants that prefer drier soil are clustered in the middle, at the top (lavender, rosemary, oregano, thyme, sage). I roughly alternate perennials (p) and annuals (a).
With the help of my children, we removed the existing plants (sedums, daylilies and black-eyed Susans) and relocated them. Then we removed the river stones and put them on a tarp. We interlaced cardboard boxes to cover the surface and prevent old plants from growing back. Using a bucket and a string, we drew the outline of the spiral and then placed pavers to hold the soil. We put some of the river stones back in the middle of the cone on top of the cardboard. Then, we piled up all kinds of stuff (branches, leaves, food scraps, etc.) that we had at hand.
We covered the whole thing with bagged soil, mixed with a little bit of sand on the top. I drew the spiral on the soil and my daughter carefully placed the largest river stones we found following a specific colour pattern.
Finally, I planted the herbs according to plan and covered everything with red cedar mulch.
Voilà! A real delight for the eye and the taste buds! And there are many other ways to incorporate edible plants into your ornamental gardens. The sky is the limit!
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