An herb spiral is a raised garden bed that is both beautiful and functional. It’s perfect for small space food gardens, but can also be tucked into ornamental landscapes to supply fresh herbs for the kitchen. Like other types of raised beds, spiral gardens are low-care spaces and their unique shape allows the gardener to plant both sun and shade-loving herbs in the same bed. Intrigued? Keep reading to learn more about building and gardening in a spiral herb garden.
What is an herb spiral?
An herb spiral is a raised garden built in the shape of a spiral. It’s taller in the middle and circles down to ground level. It can be made from a variety of materials like stone or wood, and offers different growing conditions within the same bed. Herb spirals are popular in permaculture design and constructed from materials found on site. You can make a spiral herb garden as large as you want, but most are around six feet in diameter and two to three feet tall.
Why grow herbs in an herb spiral?
There are many benefits to growing herbs in a spiral garden. First, the unique mound shape of the bed means it is higher in the center. This results in excellent drainage which is important for many types of herbs, particularly those that originate from the Mediterranean region.
The raised shape of a spiral herb garden also means there are areas of the bed that receive full sun and areas that are a little more shaded. This mix of microclimates means you can grow both sun-loving and shade-tolerant herbs in a single garden. Basil and oregano are suited for full sun, while cilantro and parsley can grow in less light.
This is also a project suited to a gardener who, like me, doesn’t have professional construction skills. It makes a great weekend project and uses easily sourced materials. Finally, I think a spiral herb garden is a beautiful landscape feature. It’s attractive, functional, and an effective way to grow an assortment of herbs in a relatively small space.
The best site for a spiral garden
Before you break ground on a spiral garden, take a look around your property to find the right site. It should offer at least six hours of direct sun each day and be located near to the kitchen, especially if you’re planning to grow culinary herbs. Level ground is also helpful, especially when you’re constructing the garden.
The best materials for constructing a spiral herb garden
An herb spiral can be made from a variety of materials including stones, bricks, pavers, or wood. There are benefits and drawbacks to each and below you’ll find a closer look at these four common options. One point to note is that stones, bricks, and landscape pavers absorb heat during the day and radiate it out at night, which reduces sharp temperature fluctuations when the sun sets.
- Stones – Whether irregular shaped or flat, stone adds a natural element to a spiral garden and is both strong and attractive. Typically stones have more uneven surfaces than bricks or pavers and are often more difficult to stack. If relatively flat they can be dry stacked or you can use mortar or cement to hold them together. In my garden it seems that every time I dig a hole I bring up a pile of stones and therefore they’re an inexpensive building material for projects like an herb spiral.
- Bricks – Bricks are easy to source, strong, and flat which makes stacking them fairly easy. You can use new or old bricks, and may luck into sourcing a pile of old bricks from a construction site.
- Pavers – Like bricks, landscape pavers have flat tops and bottoms. They are generally more expensive than bricks and stones, but come in a wide variety of sizes, shapes, and colors.
- Wood – Logs, dowels, landscape ties, or other untreated wood products also make excellent materials for building an herb spiral. The wooden bed featured in the above photo from The Backyard Urban Farm Company uses three-inch Eastern White Cedar dowels for a durable and long-lasting garden bed.
The best type of soil to use in an herb spiral
For an herb spiral that is six feet across and two to three feet tall you’ll need about a cubic yard of growing medium. You can buy triple-mix or garden soil, or take soil from another part of your property and mix it with compost or leaf mold. Most herbs grow fine in average garden soil so there’s no need to add too much manure or organic materials.
How to build an herb spiral
There are four main steps to building a spiral garden: site prep, marking out the design, building the bed, and adding the soil.
1) Prep the site
If the garden is to be built on top of an existing lawn or if there are persistent weeds, either remove the turf first or lay down a layer of cardboard or a product like Sunbelt Weed Control. To disguise the cardboard you can cover it with compost or bark mulch. It will eventually break down and smother the grass beneath the bed. If the existing soil is particularly infertile, you may wish to dig down so that you can fill the area with a high quality triple mix or garden soil.
2) Mark the spiral on the soil, grass, or mulch
Use a stake to mark the center of the bed. Tie a string to the stake to help you mark the outer shape of the circle. For a six foot diameter bed, the string should be around three feet from the center stake, but you may wish to build a wider or smaller spiral garden. To mark the perimeter of the bed, sprinkle a thin line of flour or powdered lime, or carve it lightly into the soil or mulch with a garden hoe. You can also use flour or powdered lime to mark out the spiral shape in the inside of the circle. Each planting section in the arms of the spiral should be one to one and a half feet across to ensure enough growing space for the herbs.
3) Build the herb spiral
Once you’ve established the spiral pattern on the site, begin to build the bed. Lay one row of stone, bricks, timbers, or the desired material along the pattern. The outside wall of the spiral will be the lowest part of the garden and may only be one or two stones or bricks high, depending on your desired design.
Continue to stack the building material along the central spiral pattern. As you stack upwards you can add soil to the bed. This will help support the design and prevent collapse of the stones or bricks. If you’re using mortar or cement to hold the building materials in place, wait until it has cured before you add the soil. As you add additional rows to create the spiral, make each layer several stones or bricks shorter so the middle of the bed grows higher.
4) Finish the spiral by adding soil
Keep adding soil as the walls get taller. Once the bed is about two to three feet tall and filled with soil, you’re done! I recommend digging in a one inch layer of compost before planting to further enrich the soil.
The best herbs to plant in a spiral herb garden
Because an herb spiral offers slightly different growing conditions, plant herbs that prefer sun and well-draining soil at the top of the spiral. Best bets include rosemary, oregano, thyme, lavender, and sage. Herbs that can take a bit of shading and more moisture can be planted on the north side and along the bottom of the spiral. Good choices for these spaces include parsley, cilantro, tarragon, and chives. Below are my 9 favorite herbs for a spiral herb garden.
In my garden basil is an essential summer herb offering fragrance and flavor to my cooking, as well as flowers for the bees. I grow many types of basil in my garden (read more about that here) and recommend sticking to compact basils like Greek basil or Everleaf Genovese when planting in an herb spiral. Greek basil varieties grow just a foot tall while Everleaf Genovese, a beautiful and productive variety grows just sixteen inches tall.
Rosemary is a tender perennial that, like other Mediterranean herbs, thrives in sun and well-draining soil. It’s a low-care herb and only requires an infrequent deep watering if the weather has been dry. There are many types to grow and my preferred varieties are ‘Arp’, ‘Hill Hardy’, and ‘Barbeque’.
Sun and well-draining soil are all that you need to keep thyme happy. Plant it near the top of your herb spiral, making sure it receives plenty of direct light. Thyme is a low growing perennial plant with tiny, strongly flavored leaves. It flowers in mid summer and attracts bees and beneficial insects to the garden.
In my raised bed garden I love growing Italian parsley, a brightly flavored herb that can grow three feet tall. In the modest space of an herb spiral, I prefer to plant curly parsley. It grows in tidy mounds and maintains a size around a foot tall and a foot and a half across. It’s easy to grow from seeds sown indoors in early spring, but established seedlings are also easy to source from garden centres and nurseries.
I grow a variety of oreganos in my garden but my favorites are Greek and Syrian oregano which are have grey-green leaves that are delicious fresh or dried. Oregano is a Mediterranean herb and should be planted in a site with full sun and well-draining soil. The south-facing side of the spiral is the best spot for oregano.
Perhaps the easiest herb to grow, chives is a hardy, reliable perennial plant that thrives in sun or partial shade. The grassy foliage has a mild oniony flavor and can be clipped all season long. We also enjoy the purple flowers that emerge in late spring, adding the pretty petals to salads and sprinkling them over baked potatoes. Once the blooms fade, I cut the plants back hard to encourage plenty of new leaves.
Cilantro is a tricky herb to grow, often bolting just a few weeks into the harvest season. It’s not meant to last all season long in the garden and so I sow a pinch of seed every couple of weeks from mid-spring through early autumn. Planting cilantro in a spot where it has a bit of shading and moist soil can prolong the harvest of the pungent leaves so tuck a couple of plants at the back and bottom of the spiral garden. It won’t last forever, but when it does bolt, enjoy the lacy flowers that are pollinator-friendly, followed by the aromatic seed pods which can be harvested and dried as a spice.
Lemongrass is a beautiful and delicious herb to grow with a bright lemony fragrance and flavor. I love the arching, grassy leaves that make a lovely herbal tea, but we also use the fleshy base of the stalks for stir fries, curries, and other dishes. Plant it towards the top of the herb spiral where it receives excellent drainage and lots of direct sun.
This culinary herb is an attractive plant with fine-textured foliage and slender stems. The leaves have a delicate licorice-like flavor and it adds a warm flavor to salad dressings as well as chicken, egg, and lamb dishes. The plants like good drainage and don’t want to be sitting in water. The top to middle sections of a spiral garden is perfect for French tarragon.
A spiral garden can grow more than herbs!
A spiral garden doesn’t have to be reserved only for herbs. It can also be used to grow vegetables like dwarf tomatoes, bush beans, beets, compact varieties of squash and cucumbers, leaf lettuce, and other favorite vegetables.
A final tip! Label your herbs or vegetables as you plant with simple bamboo markers that are both decorative and functional.
For more posts on growing herbs, be sure to check out the following articles:
- Herbs to grow in shade
- Growing a culinary herb garden
- The 7 best herbs for container gardening
- When and how to harvest herbs
Are you thinking about an herb spiral for your garden?