Why build an Herb Spiral?
- They are eye-catching conversation starters. Instant charm.
- Herb spirals can host a lot of plants in a small area.
- They are easier to build than assumed.
- You can extend your zone in an herb spiral through the concept of thermal mass. Stones are able to absorb, store and release heat, which can modulate extremes of heat and cold in the herb spiral, dependent on the build type. My herb spiral can support one full warmer USDA Zone, as I have created a toasty little microclimate.
The Build
Account for the following:
–Wind. An herb spiral with higher stone sides and lower soil depth may provide some wind protection, depending on the height of the plants within it. If you intend to plant taller plants within the spiral, account for any wind protection needed when choosing location.
–Depth. Do you need to do any digging to make the ground level for the herb spiral? If you are digging more than a few inches (check your local ordinances), you may need to do a call before you dig to have your yard mapped for any gas, water, cable and other infrastructure lines. Do you have a soil type prone to settling? That will impact the look and stability of the herb spiral as the years pass. My soil type is a loamy clay, and seven years after our build, there is only a slight settling, noticeable at year five.
–Material. We chose an herb spiral created with pavers, to ensure it blended in with the neighborhood and matched the look of the house and porch. And we genuinely liked the stones we chose. We also chose a stone we could move and rearrange with limited help.
–Cost. If you have access the larger stones, you can create an herb spiral for low to no cost. We had Lowes deliver our pavers to the front yard and build the herb spiral on our own. My veteran discount is always helpful and I am grateful for it! Soil and other materials to fill the herb spiral may have a cost as well. You may need to top the herb spiral with more soil each year per settling.
–Time. Planning the herb spiral, calculating how many stones to buy and how large we wanted the herb spiral took far longer than the build itself. The build, from breaking ground to level the space, to planting a couple of plants in the completed spiral, took less than three hours. We hemmed and hawed over the planning of the herb spiral for days.
–Help. Most stones used to build an herb spiral are pretty heavy. You may need to have them delivered. If using irregular rocks, it may take a while to arrange the rocks in a way that will be stable. If you need to bring in soil or compost, that may require the assistance of others.
–Soil. We used a lasagna method for the initial fill. Cardboard, newspaper, kitchen scraps, cheap topsoil and compost. Each year my herb spiral needs the equivalent of around 8 gallons of soil/compost added to maintain the soil level I prefer. The soil will settle a bit every year.
–Space. Do you have room for an herb spiral? Is there enough room inside the herb spiral for plants to spread? We left a 10″ space in the herb spiral for soil and plants, based on our usage. If you plan to use the herb spiral for larger plants i.e. summer squash, your gap between stones will need to be far larger. My herb spiral is for flowers, herbs and eggplant. The purple blossoms of eggplant are so very pretty, and the plant variety I like is compact. How much space do the plants you have chosen need?
–Water. Depending in the design you choose, you may need to water the top of the herb spiral as water will flow from top to bottom. You can plant herbs and other plants with lower water needs near the top, and plants with higher water needs near the bottom of the spiral. If you will need to water it often, is the herb spiral placed near a spigot or easy access to a water source? Is it placed under eaves or a tree where it may get less water in a rain?
–Plants. You may be able to extend your USDA Zone planting in an herb spiral. Yet for the first year, it may be best to plant zone appropriate plants. Watch how they react throughout the next season. Then try to extend your zone in year two and see what happens! Many herbs are perennial, dependent on the zone. Anything perennial, take care to plant it somewhere in the spiral where it will do best, year after year. I have chives, parsley and sometimes sage that returns year after year. Consider the root system needs of the plants and whether the soil gap is wide and deep enough in the space chosen to provide for the plant. Plants that hang over the stone sides are particularly lovely.
Photos of the Build
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