Introduction: Raised Bed Garden From Roofing Sheet Metal
We live in California where there's a drought. We wanted a raised bed vegetable garden in the area where we used to have a lawn.
After looking at various designs made from wood, we decided to try using metal. The advantages are:
- It's less expensive than most wooden designs, I think.
- You can make any shape you want, and the shapes have an organic look, free of any corners.
- No precision cutting is required.
Step 1: Cut the Sheet Metal Into 2' High Sections.
We purchased corrugated sheet metal in 2' x 8' sections. It costs about $15 per sheet.
I cut each sheet into four 2' sections using a skill saw with a special metal cutting blade pictured above. The blade cost about $12. The cutting is very noise. Wear ear and eye protection.
Step 2: Connect the Sections
I screwed together four panels into a roughly 2' x 8' assembly using self tapping galvanized screws.
You're probably asking why I cut up a 2' x 8' piece of metal and then screwed it back together into another 2' x 8' assembly. The reason is that the ridges in the galvanized material have to run vertical. If they're horizontal you won't be able to bend the walls into shapes, and the walls won't hold any vertical weight.
When I was assembling four pieces I tried to put best cut edge of all the pieces on one side. Then I marked that side with a bit of tape. This best side became the upper edge.
A nice thing about the ridges and valleys in the material is that it's very easy to line up the pieces. One ridge fits into another valley. However, I did experiment with several ways of joining the pieces. Some joints have just a one inch overlap, with six screws. Others have a full ridge/valley overlap. Clearly the more overlap you have the less linear footage you wind up with.
I made sure the screw heads were all on one side of the assembly. This would become the outside of the planter box.
Step 3: Connect the Assemblies Into a Planter Box
We took the 2' x 8' assemblies outside and connected them together.
Then we played with various design ideas. Originally we planned to make 3 nesting kidney shapes, but in the end we settled on the one long U shape you see in the photos.
If you look closely at the photo you'll see rebar metal spikes every few feet, particularly in the straighter sections. These support the walls. During construction we also used buckets with rocks or water in them for weight to support the walls.
We laid down gopher wire between the walls. "L" shaped pieces of gopher wire was places all along the lower inner edge. The morning after we planted the vegetables we were very glad we'd put in this gopher wire because there were fresh gopher tracks around the outside where someone had tried in vain to get in. Actually we don't know whether it was a gopher or a mole.
One other benefit of the gopher wire was that it gave us a good idea of the square footage of our garden. We multiplied this by the desired height of the dirt to get the number of cubic feet. Dividing cubic feet by 27 gave us cubic yards.
Step 4: A Big Truck Delivered Our Vegetable Garden Soil
The soil cost about $50 per cubic yard, with a $70 delivery charge. We got 4.5 yards.
It took just a moment for the truck to dump it on our driveway, and a day to move it into the raised bed.
Step 5: A Ramp Helped Us Efficiently Dump the Wheel Burrow Loads
Experimentation and refinement resulted in a ramp for dumping the wheel burrow loads.
Two sticks crosswise were useful for stopping and holding the wheel burrow's wheel.
Some extra lift was required to raise the wheel burrow up over the lip of the raised bed and turn it vertical enough for the last of the dirt to spill out.
Step 6: Drain Pipe Was Added to the Top Edge So We Would Not Be Cut by the Sharp Steel
We chose to use 3" drain pipe rather than the more common 4". Unfortunately we could not find less than 100'. The roll cost $60. We had lots left over.
I found that a coping saw cut it lengthwise very quickly.
I connected the joint with black wire ties.