Make Lightweight Concrete Stackable Garden Beds

Making a Taller Concrete Raised Garden Bed

So let’s get on to stacking these panels to make a deeper bed. And to do that I’ll need some longer rebar than before. I picked up some pre-cut epoxy coated rebar in a 24″ length.

And to help with stacking, I’ll be using some plastic wedges. These are available for levelling furniture or fixing wobbly toilet bowls. They happen to be just the right angle to compensate for the draft angle of the mold walls.

So this is the rectangular bed I assembled in the first video. I brought in six of the 36″ lightweight panels and placed them close to where I’d need them.

Stacking the Panels

I’ll pull two of the shorter rebar then place two of the plastic wedges on the top of the end panel. Then place my first lightweight panel on top. And roughly positioning it so the holes line up with the ones below. I’ll set more wedges on the next panel and pull another short rebar.

I can set this next panel then work the longer rebar into place. The rebar should not require much force to slide it in.

I’ll slide another length of rebar in to temporarily hold that first panel in place.

I’ll work my way around the bed placing wedges, pulling short rebar and replacing it with long ones.

Now, it’s not a requirement to have the second row of panels in a lightweight concrete. I just happen to be making lightweight panels for this video so this is what I had. You could have your second row of panels made from regular sand and gravel concrete.

Also, I decided to alternate the colour of the second row from red to black just to see the contrast between the colours.

Now for the last panel, I’ll pull the rebar then gently slide the panel into place.

To finish, I’ll tap the rebar into the ground with a rubber mallet.

So I’m not too excited about the red colour of the perlite panels. I think they came out too light. I like the black of the vermiculite though. I think they look pretty sharp.

Lightweight Panels work for All Garden Beds

And these lightweight panels can stand on their own. They are durable enough for the starting row of a raised bed as shown in this two by three bed that I put together.

And there you have it, a stacked concrete garden bed.

Summary Comments for this Video

I like how smooth the concrete is when I use wax instead of mineral oil in the forms. And also how well the pipes come out with petroleum jelly brushed on. The shorter 24 inch mold always takes a bit more effort to remove the casting, as it has less flex. It sometimes requires a bit more gentle persuasion and patience.

I have used lightweight concrete made with perlite and vermiculite is the past, and those panels are holding up very well. I showed them in my 5 Year Concrete Garden Box video. The sand in the mix gives it the durability I like, and the reinforcements some added strength. And the lighter panels are much easier to place when building the garden boxes.

With taller beds, there will be more force from the soil pushing on the panels. In rectangular beds with panels lined up end to end, it might be an idea to tie the sides together with a galvanized wire that wraps around the rebar and is buried in the soil. This wire would be added between the stacked layers when the rebar is installed. Just remember that there’s a wire buried across the bed if you want to dig or turn the soil later.

Also longer rebar hammered into the ground will help prevent the sides from bowing out.

Also, keep in mind that deeper beds may require topping up the soil level year to year. That added weight of a deeper bed can compress the soil more than a shallow bed.

In my next video (and blog post) I’ll be making thin panels in a new mold with a brand new high strength concrete blend. I’m really excited to show that to you and, it’ll be coming right up.

So thanks for watching (and reading) and leave me a comment with your thoughts or suggestions. We’ll see ya next time.

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