In the last post I talked in depth about the amazing world of compost and earthworms. Separately they are amazing but what happens when you build a platform for the two? Magic. The next stage on our path to sustainability is “The Keyhole Garden.”
How did this happen? It all started with a conversation I had with the guys from BioArk. We wanted to find ways to reduce our kitchen waste as well as find self-sustaining growing beds for the garden. Mikkel then suggested keyhole gardens. He sends me a link about them and next thing I know, I was lying in bed at 2 AM reading about the origins of the keyhole garden. Apparently, it’s a common growing medium in Africa. For those who aren’t familiar with a keyhole garden, it’s a circular growing bed with a maximum diameter of two meters, a height of about 80 cm and a 25 cm wide cylinder in the middle made of chicken wire. There is a small wedge cut into the outer circle that abuts the inner cylinder to allow for standing access: It basically looks like a huge wheel of cheese that someone took a giant wedge from. It’s hard to visualize this, but it all makes sense when you see the photos.
How did we construct this thing?
The construction of the whole bed goes something like this. The outer wall was made of reclaimed bricks from a demolished building in the neighborhood. By reusing the old bricks, we were not only sustainable but also saved money.
The downside to having free bricks was that we had to sand down about 600 bricks so they would stack properly. The amount of time and work it took us to do this was mind-boggling. I had to keep on telling myself that this was all for a good cause. After we finished the brick frame, we starting filling in the base with carbon and nitrogen-based elements. Luckily for us, this was the fun part. We used over a week’s worth of unbroken wine bottles to fill the base – this was to allow oxygen to percolate through from underneath the growing medium. And here’s comes the good part: for each garden, we saved about one month’s worth of blank brown cardboard from the kitchen. Then you place a layer of cardboard down, soak it with water and then add horse manure and the earthworms. You make about 10 layers of this and then put 10 cm of soil on the top. Give it about five to six weeks for the earthworms to metabolize the carbon and nitrogen then you can add your wet kitchen waste (anything compostable like vegetable trim, but no onions or citrus fruits!) to the center cylinder. At this point, the earthworms go to town with all those organic materials and leave worm castings to fertilize the plants growing above it. And it doesn’t even have to be watered often because it draws water from all the fresh wet kitchen waste.
This project was truly a team effort. I think at one point there were twelve of us working on the gardens at once, and at least one point throughout the day, we were all cursing those bricks. But the results were worth it. Plants that come from the keyhole garden are incredibly prolific and best of all, everything tastes fantastic.
For those who want to build their own keyhole garden, here’s the list of materials we used for our 2 beds. And all of it was material that otherwise would have been thrown out.
- Two weeks worth of used wine bottles
- 600 reclaimed bricks
- Two weeks worth of brown (non-bleached) cardboard
- Horse manure from Christiana (they apparently have a problem giving it away)
- AND 50 hours of blood, sweat and a few tears
I hope this post inspires some of you to try to build your own keyhole garden. And if any of you need some cardboard or a couple of starter worms, please don’t hesitate to send us an email at the restaurant. There’s nothing more we’d love to do than to help others kickstart their own keyhole garden.