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Earthblock Garden Build, Urban Agriculture Summit

On Aug. 18, seven participants in the Urban Agriculture Summit, hailing from as far away as Oregon, attended a Green Thumbs Growing Kids garden build. We used Compressed Earth Blocks, made by Henry Weirsma of Fifth Wind Farms. Here’s the location – it’s like a small town of 20,000 people, in 10 city blocks full of highrises. The site will be shaded by a building to the south for 3 hours  in midday – actually could end up helping to conserve water.


Henry showed up with about 100 Earth Blocks. His farm is a little over an hour away in Cobourg Ontario. He makes the blocks from his local clay, and adds 5-8% cement. The blocks are 1/10 of the carbon footprint of a cement block. They contain far less cement and are air-dried rather than kiln-dried. While they won’t last as long as cement blocks, they are comparable to wood for longevity, and using them thus leaves more trees alive and breathing. By growing more food and composting food waste close to home, greenhouse gas emissions are reduced. Further reductions are obtained by organic practices that do not use fossil fuels for fertilizer. Each bed this size will reduce GHGe by between 1.13 and 1.38T.

Here’s the crew making sure the bed will be 1m away from the fence for kid safety, levelling the ground for the first course.


And the Earth Blocks look sharp, too. After the bed is built, we will coat the blocks with a low-VOC sealer and then let kids paint on the exterior. Raised beds warm up faster in spring and cool down slower in fall, adding length to the growing season. The thermal mass of the blocks moderates temperatures and protects the plants from extremes. You can add a plastic row cover under which Bloomsdale spinach will grow all winter.

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Henry (left) and Brad, a workshop participant.

The first course takes the longest.

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After the first course is laid all nice and square and levelled up with sand, the work goes pretty fast. We used a low-VOC adhesive between courses and between block sides. Four courses are planned. The build takes a little less than 4 hours, including introductions and lots of chatting.


Here’s Marie laying in the last block.


Here’s the finished bed. The dimensions are about 4′ x 9′, which is not too wide for little people to reach into the middle. The length is not so long that kids are tempted to jump onto the bed to get to the other side. It will happen, for sure – but less of the time. A few little chunks of Earth Block came off during the build – but each block is 4″ deep and 7″ wide so it doesn’t matter too much. Extra blocks are piled inside the bed, hoping they don’t wander too far before we get another delivery and build the next bed with students!


Finally, here’s the group, with me on the left – not pictured are Joe (taking the shot) and Anita (staff – cleaning up!) I barely broke a sweat with all the help. It was a great day, and Rose Ave. PS kids are going to be excited to continue building this new garden area. For all the photos, visit

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