Introduction: Making a Raised Garden Bed From Concrete Pavers
It may not be the most beautiful garden bed but I was happy to recycle these 2x2 foot concrete pavers that were lying around. You can make a great raised vegetable bed by building a supporting timber frame. This instructable doesn't come with exact plans but hopefully can inspire the "ah yes, I can work with that concept"
A lot of my work went into separating the bed from the ground which is seething with hungry tree roots that have crippled most other attempts of growing vegetables. If you don't have that root problem then you could probably skip the plastic lining step and simply bury the base of the pavers in the ground. Drainage is facilitated by a layer of course sand at the bottom and 3mm or so gaps between the pavers.
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Step 1: Foundation
Stake out the space you're going to use and get the ground very flat using a shovel and plank of wood. It need not be level. I kept a few degrees of downhill slope to assist drainage. Flat is very important so that the timber frame sits well on the lip of the bed.
Additional steps that I added but may not be necessary was a brick and earth foundation covered with old carpet and a thick plastic liner to stop tree roots getting into the bed.
Step 2: Building
At least 2 people and a bunch of propping sticks are used to get the pavers into position.
The top frame is made of 70x35mm treated pine, and is made to hang over the edge of the pavers by 30mm. L brackets are used to hold the frame together.
My quick and dirty approach to sitting the frame onto the pavers is to use large coach screws, which stop the pavers falling over. See 3rd photo below. I figured the pavers can't fall in once the bed is full of soil. It really would be better engineering to solidly attach the frame somehow to the pavers by drilling them and maybe using L brackets and bolts. The way I've done it is working great for me but I don't have earthquakes where I live or kids climbing on it.
Step 3: Base Frame and Drainage
I put a simple frame of treated pine and coach bolts around the base. To thwart the tree roots the plastic liner on the foundation is folded up under the pavers and is held in place by the timber. I have a drainage hole in the plastic on the downhill side of bed
A step not pictured is that I filled the bottom of the bed with a well drained sandy mixture and lined the gaps between the pavers with a strip of shade mesh to stop them clogging with soil.
Step 4: Filling and Planting
It took a lot of compost to fill the bed but everything is growing well and drainage seems to be ok even in some heavy rainstorms. The net in the picture is draped over some stakes in the bed and is to keep the possums and birds off. The bed is a great hight for planting and picking!