How to build a Brick Herb Spiral
We have had an allotment for years, and I've always wanted a Herb Spiral. This year we've had the opportunity to re-arrange things at our plot, and the perfect spot was found. We decided to build a Brick Herb Spiral and this is how we did it.
Herb Spirals and Permaculture
A Herb Spiral is a lovely feature to have in any growing space, like the ultimate raised bed.
Herb spirals allow you to plant masses of herbs in what is, in effect, a compact 2 metre diameter space. So it's a great space saver as well as being such an attractive feature.
But rooted in permaculture design, herb spirals also have a number of highly practical features.
Depending on where the spiral is built and the direction of the sun, some plants get longer periods of sunlight in the day and some get more shade. You water the spiral from the top, where the sun loving herbs (such as rosemary) are planted. Then the softer herbs that need a lot of water are planted at the bottom, and the excess water flows down to them.
The bricks absorb the sun during the day, keeping the earth in the herb garden warm at night.
Finally, you can design your spiral to have a pond or bog at the bottom, to create a habitat for frogs and lizards. We haven't done that yet, but we built ours in such a way that we can incorporate a pond later.
Why a Brick Herb Spiral?
There are many ways to build a herb spiral. Some with the spiral design built in stones, some in wood. Having looked at all the different designs and worked out what building material was easiest to source quickly and inexpensively (free, as it turned out), we decided to use repurposed bricks.
I kept checking on Facebook Marketplace for a load of old house bricks to come available. I was happy to pay for them, but this was during the COVID-19 lockdown and lots of people needed materials for outdoor projects. So every time I saw bricks available, they were gone before I could ask.
This turned out to be a blessing in disguise. In the end a lovely chap delivered a whole of hardcore to our allotment and we were able to pick out the bricks from that. He was glad to be rid of the hardcore, so he gave it to us and delivered it - al for nothing. We were able to put some of the rubbly bits into the spiral itself, to reduce the amount of compost we had to use (more on that later). So it all worked out really well.
What other materials did we need?
Once we'd sourced the bricks, there wasn't much else to find really.
We decided to cover the ground around the edge of a spiral with a weed suppressant membrane. This is because our allotment is prone to invasive weeds such as couchgrass. We then covered that suppressant with cardboard from the shop as double insurance against the weeds. That cardboard will break down eventually.
Then we just needed well rotted horse manure, horticultural sand and multi purpose compost to fill the spiral, ready for planting.
We got an added bonus when the hardcore was delivered: an old chimney pot. Not generally featured in a typical permaculture herb spiral, we decided we had to use that!
How we built the Herb Spiral - step-by-step
1. We chose an area of the plot which is relatively flat, with plenty of sun for the herbs. We laid the bricks out so we were sure it would fit the space, keeping it at around 2 metres in diameter.
2. We covered the area with a weed suppressant membrane.
2. We covered the weed suppressant with cardboard, which will eventually rot down. Andy put a spike in the middle of the cardboard with a meter long piece of string attached. He then drew a circle 2 metres in circumference directly on to the cardboard, in pencil.
3. We laid an outline of bricks on top of the pencil circle, and spiraled it in towards the middle until we were happy with the shape. Now we were ready to start building.
4. We worked our way around, building up the spiral. We simply placed the bricks across one another. Someone asked us if we used cement, we didn't. We did spend time removing cement though. These were bricks from a hardcore load, some of them had cement on them which would would have prevented them from laying flat. We used a geology hammer (usually for fossil hunting) to remove the cement - you can just see it in shot here.
5. Somewhere around this point, we realised we weren't going to have enough bricks. I had reckoned on 120 but we needed more, so work stopped.
I asked around and 2 friends kindly offered us some bricks they had laying around in their gardens. We arranged to collect those.
6. We carried on building the following weekend until it was finished - in the end we needed 160 bricks. We built up the middle section to around 60cm high. We put some hardcore in the middle of the spiral to help with drainage, plus it meant we needed less soil to fill it. We then filled the whole spiral with a mixture of well rotted horse manure, horticultural sand, our own compost from the allotment and a general purpose compost.
7. Finally, we planted herbs in the spiral. Some were from around the allotment, others were from our garden at home, some I'd grown from seed especially for this, and some I'd bought on Ebay.
And then we were finished!
Ta-da!
Herb Spiral DIY - the materials we used
In summary, to make our herb spiral we used:
Weed suppressant (you may not need to use this)
Cardboard
Recycled house bricks
Well rotted manure
We absolutely love our herb spiral. It is the perfect project for anyone interested in permaculture design and/or someone who wants to grow a lot in a small space.
Here is a walk through video showing you the herbs we planted.
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