Designing a Spiral Herb Garden

Designing a Spiral Herb Garden

By Melanie Stuve, Master Gardener

Some projects are born out of curiosity and intrigue, while others are born out of necessity. When we discovered that our yard had a roadbed running under a good portion of it—making in-ground planting impossible—we knew we had to get creative to use the space for gardening. We built raised beds for vegetable gardening, which was fairly straightforward, but while researching alternatives, one particularly interesting idea stood out: an herb spiral.

 

The concept of an herb spiral is simple yet effective. Soil is mounded highest in the centre (or top) of the spiral and gradually becomes shallower toward the outside edge, or tail. This creates a range of growing conditions within a small footprint. Herbs that prefer drier conditions are planted at the top—such as rosemary (Rosmarinus officinalis)—while moisture-loving herbs, like parsley (Petroselinum crispum), are planted toward the bottom.

 

My husband and I love projects and are avid do-it-yourself gardeners, and I would rate this project as a relatively simple one. It can become more complex if you choose to build a tall spiral or use materials such as bricks or mortar. By keeping the spiral smaller and using simple materials, the project remains very manageable. An herb spiral requires only a few basic materials; in our case, stones, cardboard, and soil. We made a trip to a local landscape supply company and hand-picked medium-sized black granite stones. We estimated how many we would need and, by some miracle, ended up with exactly the right amount. For soil, we chose a four-way mix, which provided good structure, drainage, and organic matter for a variety of herbs.

 

We began by choosing a sunny location and laying cardboard directly on the ground to suppress grass and weeds. Our original spiral was built in 2022, but we rebuilt it in 2024 after grass began creeping in. During the rebuild, we decided to mulch the entire garden area to further prevent grass from growing into both the spiral and our raised beds.

 

Once the cardboard was in place, we laid the first layer of rocks in a spiral shape. Each layer of our spiral is approximately one foot wide. After placing the rocks, we filled the layer with fresh soil and continued building upward, starting from the centre. We alternated between adding soil and rocks until the spiral reached our desired height and size. Finding rocks that stack well takes some trial and error, but adding soil as you go helps stabilize the structure as height is added.

 

 

We also chose to install a dripline irrigation system in our herb spiral. We use a Lee Valley irrigation system with a sunrise timer for all of our raised vegetable beds, and incorporating it into the spiral has made watering much easier and more consistent—particularly for plants such as tomatoes that benefit from regular moisture.

 

 

For taller or larger spirals, it is important to consider sun exposure. Pay attention to which side of the spiral receives the most sunlight and which side is more shaded, and plant accordingly. The low side of our spiral is on the south side, and because our spiral is relatively short, we do not have a significantly shaded area. At the top of the spiral, we planted rosemary (Rosmarinus officinalis), thyme (Thymus vulgaris), and oregano (Origanum vulgare). About halfway down, on the north side, we planted basil (Ocimum basilicum). Lower in the spiral, we planted anise hyssop (Agastache foeniculum), sage (Salvia officinalis), and parsley (Petroselinum crispum).

 

There are a few important considerations when planting an herb spiral. Some herbs are perennial in Manitoba, while others are grown as annuals. Although plants can be moved from one season to the next, it helps to plan ahead. In addition, some herbs can be quite aggressive and may require regular maintenance to keep them from overtaking their neighbours. I learned the hard way not to let my anise hyssop (Agastache foeniculum) go to seed. To keep plants growing vigorously, we apply an organic fertilizer about once a month. Weed pressure has been minimal, especially since we mulched the surrounding garden area.

 

We harvest herbs regularly throughout the growing season and do one final harvest before frost. Most of our herbs are frozen for use in winter cooking. With basil, we like to make pesto or blend chopped leaves with olive oil and freeze the mixture in ice cube trays for easy use. After harvesting, we leave the plants standing over winter and let the bunnies enjoy what remains. The dried stems also help trap snow, which provides natural insulation and protection for our perennial herbs.

 

Overall, our herb spiral has been a wonderful addition to our garden. We enjoy a generous harvest of herbs throughout the growing season, and the spiral is easy to care for and maintain. It also adds visual interest and structure to our yard.

 

If you would like to see our herb spiral in person, you can visit our yard during the Manitoba Master Gardener Garden Tour this summer on July 18, 2026.