1. Collect materials and supplies
Our raised garden beds are approximately 4x6 feet each (51.5x72 inches to be exact). You can imagine a structure as a box with no top or bottom. We designed this raised garden bed to be small enough that you can easily reach the middle of the box. If you have shorter arms, you might want to consider shortening the sides by 51.5 inches.
To build a box, you will need the following supplies:
4) 2x8x8PT wood
8) 2x4x8PT wood
5 pounds a box of 3" long stainless steel screws
2) 10ft corrugated galvanized steel sheet
Base Paver Blocks (optional, but highly recommended)
2. Cut all wood to size
The easiest way to complete this project is to cut all the wood at the same time. Instead of just building it, we'll have all the parts ready and then move on to assembly when everything is ready.
There are only three different sizes of lumber for the main frame. Here's your cut:
8) 17 inches long 2 x 4 pieces
4) 72 inches long 2 x 4 pieces
4) 48 inches long 2 x 4 pieces
For shorter sections, a miter saw can be used if convenient. We set up a station for ours so that we could make the same length cuts over and over again. This makes working with all duplicate clips fast.
That's it! The 2x4s form the entire frame of the raised garden bed. Inside, we will place and fix the corrugated steel. But for now - let's cut the parts needed to make the main box. After cutting the above parts, you can move on to the next step.
Remember - if you want to make two raised garden beds, double everything we say. These instructions focus on making the garden beds to keep things simple.
3. Assemble the raised garden bed top and bottom frame
If you haven't reached the final position at this step, you may want to move outside. Start by pinning the bottom rectangle of the bed together. Use those 3" stainless steel screws. They stand the test of time and won't rust. Of course, if you live near the beach - all bets are off!
Use a large rafter block to make sure you keep the box square and the planks together when you hold the box. Continue making the top and bottom frames before attaching the vertical struts. Remember - we try to be efficient by doing as many repetitive tasks as possible! 4.
build vertical pillars
Since we're attaching the two 17" vertical pieces to each other before attaching to the top and bottom frames, we want to prep these first. Start by placing three screws on the edge of one of the short boards.
We used an impact driver to join the boards together.
5. Attach the vertical struts to the top frame
Once assembled, attach the vertical struts to the bottom frame. Do this by pre-drilling the holes with a 1/8" twist drill bit. Follow up by screwing the vertical pieces to the bottom frame.
6. Attached to the bottom frame, horizontal and square
Now, did I mention you attach the struts to the top frame? I'm not lying. Once all four double posts are attached, it's time to get a friend to help you turn the whole thing over and place it on top of the bottom frame.
Then try to level and straighten everything as best you can. Start the drilling and tightening process again. However, before tightening the final fasteners, do another round of squaring.
7. Prepare the base for your raised garden bed
Once you're ready to place your raised garden bed, you'll need to mark its final location and prepare the area. You can use a tape measure and spray paint or some other marking material to create an exact outline of where the box will sit.
If you want the box to be on the ground, it needs to be level. This probably means digging a "trench" for the 2x4's so they don't wobble or tip.
We actually decided to put our raised garden beds on a lap of pavers. This will keep the pressure-treated wood off the ground - extending the life of the bed. This may be a standalone project. Suffice it to say, you'll need a flat surface to place this brilliant masterpiece on. This requires some preparation of the area so that the raised garden beds lie flat on the ground.
8. Cut the corrugated steel to a certain size
Once the frame is in place, you can start cutting the corrugated steel to size. It goes inside the frame. The idea is to completely separate the dirt from the pressure-treated wood. That's why these raised garden beds are 25 years or more old.
If you can, use a pair of metal scissors to cut out the panels. Metal saws are really messy.
9. Use a stapler to secure the corrugated steel to the wood
We recommend using a narrow-crown stapler to secure corrugated steel to the inside of a pressure-treated raised garden bed frame. Some great cordless tools that we love include the Ryobi P360 Narrow Crown Stapler and the Milwaukee M18 Narrow Crown Stapler.
The height of the corrugated steel should be such that it is slightly below the frame and falls into the ground. That's a good thing, but you might want to dig a little deeper. It ensures that runoff water drains completely into the ground through pressure-treated timber.
We actually recommend running a large silicone bead in each of the four corners before filling the box with dust. This further prevents water from running over the steel and hitting the pressure-treated wood.
10. Place your top
Instead of pre-cutting the top 2×8 boards, we put them on top and marked them in place. Once we knew how much overhang we liked we cut them at a 45 degree bevel. Pre-drill holes on both ends, then secure them together with more stainless steel 3" screws.
You will also need to screw these 2×8 boards into the frame from the top along the perimeter. Overall, we like how they sit more or less in the center of the frame. This allows you to have as much interior overhang as exterior overhang.
When we're done using our raised garden beds, you can easily sit on them without feeling like it's going anywhere. 11.
Fill with topsoil and enjoy!
The final step is to fill the raised garden bed with topsoil. Hopefully you can find some cheap filler and sprinkle it with nice garden soil for veggies or plants. You may also want to consider adding some gravel for proper drainage. Broken rock may suffice.
As a tip, use the hose to flush out the dirt when filling and releasing any areas that may be problematic or create large voids later. If you need advice, check out our best garden hoses article for inspiration.
