Make your own Concrete Garden Boxes! Build the forms and precast your own 36″ reinforced concrete panels that lock together to make long lasting and durable concrete garden boxes. See the complete build video that shows step-by-step how to make the plywood molds for the precast garden boxes. An alternative to concrete garden edging.
Here is the weight of 3 panels that are cured: . 48″ – 69lbs, 36″ – 50lbs, 24″ – 33lbs.
How much concrete does it take to pour each size of panel? Here’s the approximate square foot volume of each size of the 2.5” thick panels:
24” panel = 0.23 cu ft
36” panel = 0.36 cu ft
48” panel = 0.49 cu ft
Bags of ready mix concrete are sold in various sizes. Here is how much a bag of Quikrete will make:
40lb bag = 0.30 cu ft
50lb bag = 0.375 cu ft
60lb bag = 0.45 cu ft
80lb bag = 0.60 cu ft
Check the instructions on the bag to see how much it makes.
Background for the Cast Concrete Garden Boxes Project
Hi is Kent from Man about Tools and today we are building plywood moulds to precast our own concrete garden box panels.
These panels link together to create long lasting, rot proof concrete garden boxes.
Precast concrete raised garden beds.
If you’re like me then you’ve made many wooden garden boxes only to see them rot away over time. Now, I know wooden boxes have their place and they are cheap and easy to build, but they just don’t last.
I’ve used plastic liners, made them from longer lasting red cedar, bought a truckload of cheaper culled lumber and no matter what I do they still rot away.
So I decided to try making some boxes from concrete. One option is to build plywood frames, stake them into the ground and pour them in place. In a similar fashion as pouring building foundations or retaining walls. That does work well, and I like that option if you have the materials.
But instead, I want to make a more decorative, unique garden box, one that might be more suited for flowers, or closer to the house, instead of a large vegetable garden.
Poured concrete raised beds.
The panels that I make interlock in the corners in a straight line or at a 90 degree angle. I cast in plastic pipe so they lock together with rebar.
Pouring your own concrete panels gives you the flexibility to modify this simple design to your liking. You can easily change some of the dimensions to make them longer, shorter, taller, or thinner. You can also combine panels of different lengths as I’m going to do in this video.
I have two identical moulds that make a 48 inch long panel that is 8 inches tall x 2 1/2 inches thick.
I’m going to make 4 new moulds similar to that original design but, I’m going to shorten the length to 36 inches. Having a box 3 feet wide can make it easier to reach in to plant and weed.
DIY concrete garden boxes.
Concrete Garden Box Sides – the Build
Here’s how I build the forms to make the concrete panels.
One sheet of 3/4″ plywood is enough for 4 forms. I’ll also need a length of 5/8″ material 3″ wide for the decorative insets (104″ in total). And a 4x4 – 32″ long that I’ll rip into a 2 1/2 x 2 1/2 inch block to hold one of the pins. These pipe holder pins are made from 5/8″ diameter doweling (16″ required).
Here’s the main parts of the mould. A base, the inset, the sides, the ends, and pipe holder pins. Cast into the concrete there’s a reinforcing stiff wire grid, PVC pipe, and wire loosely wrapped around the pipe.
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