The spiral comes from the world of permaculture and the general principle is that by creating a rising spiral we can create a series of microclimates which then favor different species of plants – and thus we can grow all the herbs we need for cooking within just a few meters of our kitchen door and have fresh spices all year round. If a plant prefers direct sunlight, it will be on the south-facing side; if it needs shade, on the north-facing side. Some herbs also prefer rockier, drier soils, and so we fill the top-most section with sandy, almost gravel soils, transitioning gradually to a mixture of sand and potting soil to potting soil to heavily composted potting soil – with even a basin of water at the bottom to let us grow things like watercress which need to be full-time in the water.
By replacing the bricks in the walls in certain places with things like bundles of sticks, we also create habitats for all kinds of beneficial insects –and the basin of water at the bottom can help us shelter frogs and other critters crawling through our backyards looking for a home – not to mention offering a water source for bees, the best of all garden bugs.
How to do it
When you’ve got the right spot, mark the center with a stick, and tie a length of string one meter long around it. Turn the string to mark the boundary of the circle, and then lay a layer of cardboard or old newspaper (no need to buy anything new for this –just make sure you take all plastic off before you lay it down) all along the circle you just marked. This layer will mulch whatever you have lying there underneath (the paper and cardboard will decompose as well) and keep weeds from popping up into your spiral. Ideally also you should have the top of your spiral facing north – it just works out best this way, trust us.
Next, lay out the rocks to form the perimeter, and trace out the form of your spiral. On the outer edges they won’t need to be more than one rock deep, but on the inside you’ll need to build it up higher (remember we’re hoping to get it about one meter high – not a rule, but a nice guideline). Lay gravel (whatever you have on hand – again, no need to buy new stuff for this!) below for drainage, and then lay soil and compost above, gradually increasing the portion of gravel on the surface as you get towards the top. At the bottom, create a little submerged basin for the water – think of it as a little pond.
Water the whole spiral well and let it sit for a brief time and then plant away! Herbs that like drier soils (sage for example) should go on top; herbs that like it wetter (mint –though be careful, it can take over!) should go lower down. In between –well, just pick your favorite spices, find out what kind of climate they like and then stick them in where they belong!
In all, the construction shouldn’t take more than a day – less if you do it with friends and family – and it can really change your entire garden, bringing in a host of new species of plants, insects, and other animals while all the while making your cooking a whole lot better and reducing your carbon footprint (no more imported spices!).
Really, what more could you want from a day’s work outdoors? As the permaculture people say: "All the world’s problems can be solved in a garden."
This article can be found in the March 2010 edition of the Sunbeams Newsletter.