by Kristen Andersen
This summer, the Harris Seeds and GardenTrends trial grounds have expanded and now include a home garden trial area where we can test new gardening trends, techniques, and supplies. Members of the GardenTrends team suggested we include a design that has become quite popular among home gardeners: a raised spiral herb garden!
The trials team was excited to add this unique raised bed to the garden layout, and now that it’s finished we are even more excited to watch our herbs grow. A raised spiral garden can be constructed in any desired size and with a variety of materials, making it a great way to add an architectural element to small or large garden spaces.
We chose to construct our raised spiral garden with flagstone retaining wall blocks, although other gardeners have used wood, brick, field stones, or gabions. There are a few different ways to approach the construction of a raised spiral bed. The method that we used could help you to build your own raised spiral herb garden.
1. Level the soil where you plan to construct the spiral bed. If the area is grassy or weedy, you may want to remove the vegetation or cover it with weed cloth, cardboard, or another weed-blocking material prior to laying the stones.
2. Using a measuring tape, string, or other method, draw out the shape of the spiral. Be sure to consider the size of the stones and allow enough space for planting between the walls of the spiral. Place the bottom of the spiral toward the North side of the garden area (if you are in the Northern Hemisphere) where it will receive less sun. Another option is to add a small pond at the bottom of the spiral.
3. When placing the first layer of stones, use a hoe to lower the soil level where the stones will sit so that they rest a few inches below the soil. This will help to keep the foundation stones in place. While doing this, be sure to keep your soil level! Place the first layer of stones around the shape of the spiral and adjust their positions if needed.
4. Continue to add layers of stone in the shape of the spiral. For improved stability, overlap the stones with each new layer. We found that adding some soil to the spiral during construction helped to hold the stones in place. To make the spiral shape more visible, we chose to reduce the number of stones used in each new layer.
5. Once you’ve built the spiral to your desired height, fill the bed and any gaps between the stones with soil. Choose a good quality soil with plenty of organic matter. Water the bed to help the soil settle into the space.
6. When choosing the plants for your raised spiral garden, consider the different growing conditions that exist within each section of the spiral. The plants at the top will receive the most sun and have the most soil drainage, while those at the bottom will have the most shade and moisture. Our raised spiral garden is now home to a variety of herbs: dill, basil, lavender, parsley, and mint.
The raised spiral garden in the Harris Seeds and GardenTrends Home Garden Trial Bed took only 45 minutes to construct, and is a beautiful addition to our gardens. The possibilities are endless for creating a unique design of your own!
Kristen Andersen is the Trials Manager at Harris Seeds and GardenTrends. She has a Master’s Degree in Plant Breeding and Horticulture from Michigan State University and a Bachelor’s Degree in Plant Science from SUNY Cobleskill. Kristen comes from a multi-generational farm where she developed a passion for agriculture and gardening. She arranges all Harris Seeds trials at our location in Rochester, NY, as well as with grower cooperators located around the country, to ensure that we offer varieties and products of the best quality that will make our customers more successful.
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For our spiral raised bed, we used retaining wall pavestones from a home supply store. They measure 4 in. × 11.75 in. × 6.75 in. and we stacked them up to 4 blocks high, making our raised bed about 15 in. tall at the tallest point.
How y’all was this spiral garden? What size were the blocks that were used?
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