A herb spiral is a garden design element which allows us to grow a variety of medicinal and kitchen herbs in an economical and varied space. They are quite straight forward to build but a good herb spiral with a variety of species which keeps giving out every year takes a bit of forethought. Let’s take a look at the features of such a design, and these principles can be put together to suit your local situation; water, climate, light availability and suitable species.
If you build a mound, any location on that mound will have slightly different microclimates. The top will be drier than the bottom. Provided both sides are exposed, the east side will have more morning sunlight and the west will have more in the evening. The side facing the equator (south side in the northern hemisphere and vice versa) is going to be sunnier than the opposite side which faces the pole. The local conditions of the garden may supply chill or drying winds or frost from a particular direction, whereas the other side may be sheltered.
So you should select your plants and position them according to which conditions suit them best, in order to create a diversity of habitats. This may require a bit of homework, but the more research you do at this stage, the ore sustainable will be the design. Paying particular attention to light and water when choosing plant locations is key.
Oil-rich herbs such as rosemary, thyme and sage can be grown on the dry tops and sunnier exposed sides. In the northern hemisphere, the moist and sheltered base on the northerly side is perfect for green foliage herbs such as mint, parsley and coriander. [Note: use a pot for the mints to contain the roots and stop them taking over the spiral]. Some designs even create a small pond or bog area at the base of the spiral for plants such as watercress.
Some plants are great pest deterrents, for example, basil, calendula, and French marigold. Other herbs attract insects, such as ladybirds and bees, that feed on pests. Lemon balm, marjoram, chamomile and French marigold are particularly useful for this. Borage and chamomile are good for improving the growth and taste of neighbouring plants. Close interplanting (polyculture, also known as companion planting) of many different species, can create mutually beneficial relationships between the different herbs and establish a healthy, stable and diverse environment, attracting a range of attractive and useful wildlife.
Herb spirals can be quite flexibly constructed. Paving slabs or concrete is no obstacle as they can be built on top of them. Specific soil types can be catered for within the structure of the spiral by adding sand or gravel for drainage.
In conclusion, we may say herb spirals offer an intelligent design solution which utilises vertical and horizontal gradients, a diversity of microclimates, varied fresh food cultivation options and an ergonomically accessible resource for not much outlay.
From Permaculture Northern Beaches: How To Build a Herb Spiral
If you are interested in the science of food cultivation and wildlife conservation, ADL have a variety of courses to show you how.
References
Coggins, Josie. Create A Herb Spiral. Centre For Alternative Technology, Powys, 1998.
A37: Making a Herb Spiral. Garden Organic Online (PDF Document). Date & Author Unknown.
By Andy Patterson