Creating a herb spiral at your backyard is a simple way of planting many species of herbs on a small space. There are several benefits of planting on a spiral: 1) the rock warms and dehumidifies the soil; 2) the extended edge, wrapped in on itself provides a wide diversity of conditions, creating high productivity in a small space; 3) easy to water and harvest.
The scale of your herb spiral is usually depend on your need. Typical spiral is about a metre from the middle to the edge, and the center is about a meter above the ground. This will enable you to reach the center from the outside of the spiral. A smaller spiral tend to loose the warming effect of the rocks while a bigger difficult to build unless you put two spirals together in a yin-yang pattern.
What to plant? A Herb Spiral offers a variety of niche’s for the herbs. Mitra Ardron has several tips. He suggests at the top, the dryest soil found is suitable for Rosemary. As it is getting wetter as the water drains down towards the bottom you may plant other herbs – turmeric, chives, ginger.
To provide shade, bigger and leafy herbs can be planted near the spiral or in the spiral. The niches between the rocks should be planted with small herb ground covers like Pennyroyal.
Rampant herbs like Basil in the sub-tropics, are better planted outside the spiral. While the herbs are growing to full size, some of the space between them can be taken with small annuals like Rocket.
Watch the video to learn more or you can download this tipsheet (pdf).