Can you use concrete for garden beds?

Yes, concrete can be used for garden beds. They are easy to make and very long-lasting. They do not rot and can hold the heat of the sun for a warmer bed.

Are concrete garden beds safe?

Concrete garden beds are generally safe to use. Concrete is a well used worldwide material that is used around many plants with no visible negative effect.

Are concrete beds good?

Concrete beds are a durable and low-maintenance option for gardening.

Is it safe to use railroad ties in vegetable garden?

It is not safe to use railroad ties in a vegetable garden.

How to Create Raised Concrete Garden Beds PART 1 - Precast Molds -

Assemble the SIDES

Now assemble the Sides with glue and screws.

I attached a stop strip to my workbench and onto it I attached two hold down clamps. The clamps quickly and securely hold part C to the table. I also attached an end stop to align the ends of B and C.

Hold down clamps - man about tools cast form mold concrete garden boxes — Hold down clamps

Then apply a small bead of exterior wood glue to the side and press it into place. I drill a pilot hole into the hold-down strip then run in a screw.Then drill pilots thru the side all the way down and secure it with screws. Check each assembly that the L shape is 90 degrees.
Set these aside for the glue to set up.
The Sides have a small square Stop Block to hold the ends in place. Rip and cut these to length.

Drill pilot holes in small square stop block - concrete garden boxes — Drill pilot holes in small square stop block

Then pre-drill these as well.

Assemble the ENDS

Now assemble the ends parts E and F.

I marked the center of each to help with alignment and also used the hold down clamps to secure the pieces during assembly. Like before, apply glue, drill, and attach with screws.
Drill pilot holes into E and attach the Blocks with glue and screws.

Mark the side assemblies and attach the small square Stop Blocks with glue and 1″ screws.

Make the INSET

Next we will make the angled Inset.

I used 5/8″ material, and beveled the sides 30 degrees on the table saw. And cut to length on my miter saw also at 30 degrees.

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I attach the Inset part to the base by pre-drilling with a countersink, then attaching it with glue and short screws.

Lastly, I’ll cut the 5/8″ Dowels to length and chamfer the end on the disc sander, or you can round off one end with coarse sandpaper.

Glue dowels into block and sides - man about tools cast form mold concrete garden boxes — Glue dowels into block and sides

Glue these into place and let the glue fully setup.
Cut a short test piece of half inch PVC electrical conduit.

Use this to test fit the Dowel Pins. Use some sandpaper to slightly reduce the diameter of these dowels so the pipe slips on easily. The inside diameter of the pipe is bit less than 5/8″.

Fill the screw holes with wood-filler, let it dry completely, then sand smooth. Also fill any gaps in the plywood and add some filler to the inset where it meets the base. Give everything a light sanding to break any sharp edges.

Test Fit and Assembly

With pan head screws, assemble the form using the layout lines as a guide. Check that everything is square, fits tight, and there are no gaps.

If there are any variations with each assembly, you may need to try different part combinations to see what fits together best.

Label parts - garden boxes — Label parts

Label each mould assembly one through four. And also label each part assemblies with the corresponding base so you reassemble them the exact same way each time you use them.

Apply Finish

I apply several coats of Polyurethane Finish, lightly sanding between coats.

I used four coats of this durable flooring finish. Wet cement is very corrosive so you want to protect the wood to get the most life from your concrete forms.

Pipes and Wire

Cut the PVC conduit down to length.

Wrap wire around pipe to reinforce concrete - cast garden boxes — Wrap wire around pipe to reinforce concrete

Also cut a 30″ length of stiff wire and wrap it loosely around the pipe. This will reinforce the concrete and give it strength where it is the thinnest.

Final Assembly

Cut a section of Concrete Reinforcing Mesh to size with small bolt cutters and have it ready to lay in the wet cement.

This will make the concrete panels very strong.

Shims to adjust overall panel length to 36" — Shims to adjust overall panel length to 36″

This is where I remembered that not all 3/4″ plywood is fully 3/4″ thick. Most is now slightly undersized and I laid out the parts for actual 3/4″ plywood. It’s an easy fix by adding a few slim shims.

Add wire and pipes on final assembly - concrete garden boxes — Add wire and pipes on final assembly

Once assembled, the molds need to be made water tight. I use a small bead of Latex Caulking to do this.

Apply Caulking

Latex works well as it’s not overly strong and will allow you to disassemble the mold easily once the concrete sets up. Don’t use regular silicone for this. It’s too strong and will be difficult to remove later. Latex caulk is all that’s needed.

Level Forms

Place the moulds on a strong and secure surface and level them in both directions.

Once the caulking is dry, spray the mould with a releasing agent to keep the concrete from sticking. I used Vegetable Oil Cooking Spray for this.
UPDATE: Cover the pipe and pipe wrap wire with a cloth to keep the oil spray away from it during this step.

Continued on the Next Page

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