Tools needed to create the raised garden bed

While coming up with this design, I had three goals in mind:

  1. Build a raised bed that would be functional for growing vegetables (holding soil at least 18” deep) and would also support an 8’ high trellis for privacy.

  2. Stick to a design that would require only tools I already owned. Since my power-tool collection is more the homeowner variety than a carpenter’s workshop, this meant a drill and chop saw. (You could also get by with a circular saw.)

  3. Finally, to adjust the design so it would maximize the yield I could get from dimensional deck/fencing – lumber available at my local home center.
Planks of cedar lumber

In choosing a material, I opted for cedar over pressure-treated lumber for longevity, the look when weathered, and because it sits better with me for growing vegetables. With a plastic liner, however, you could use modern pressure-treated lumber for about two-thirds of the cost. Also, with a mind to longevity for the walls of the bed, I used 5/4 x 6" deck boards (shown on the left in the photo beside) instead of 1" x 6" fence boards (actual thickness of 1" versus under 3/4").

Measuring the lumber

The yard layout suited a long bed, which allowed me to use full 8’ boards for the front and back walls. Since I wanted it to be four boards high, the most efficient yield for the ends was to make the width 2’ (10 deck boards total: 4 front, 4 back and 1 board per end). I set up a stop on my work table and cut all the end boards to length, which was actually just less than 2’ since the saw kerf eats up some of the board. If you have less space, you could go with a 6’ by 2’ bed (8 deck boards each cut into a 6’ and 2’ length) or a 4’ by 2’ bed (6 deck boards).

Assembly diagram

To ensure a stable trellis frame, I built the vertical supports into frames instead of simply tying them to the back corners of the box. I built three frames so the trellis would also be supported in the center. This made it easy for me to get the structure squared up by building the end and center frames on my flat worktable and later simply stringing them together with the 8’ deck boards near the final location of the garden box.

Material List (as shown in photos)

  • 5/4” x 6” x 8’ cedar deck board (10)

  • 2” x 4” x 8’ cedar deck board (8)

  • 4’ x 8’ cedar horizontal lattice (2)

  • 2" Screws

  • 3" Screws

  • 25 L garden soil (30 bags)

  • 2’ x 8’ weed barrier

  • 2’ x 20’ vapor barrier
Measuring four deck boards stacked side by side

To maximize the amount of privacy provided by the trellis, the back leg of each frame is a full 8’ long 2” x 4”. I determined the height of the front leg by measuring four deck boards stacked side by side. For the lumber I used, it was 21 7/8”. I adjusted the stop on my table for the chop saw as needed and cut all three front legs.

Determining the length of the spreaders for the frame

I determined the length of spreaders for the frame based on the end boards less the thickness of two 2" x 4" (the front and back legs) and one deck board (to account for the stagger of boards in the corner). For my lumber, it was 20 7/8". I had estimated these measurements when sketching things out for my wood order but laid out the actual boards to finalize them before cutting. Again, I adjusted the stop on my table for the chop saw and cut six spreaders.

Marking the height of the cut front verticals onto the back trellis supports

Before assembling, I marked the height of the cut front verticals onto the full-length back trellis supports so I could easily ensure I put the top spreaders in square.

Image left: Notched boards. Image right: Cross frame.

I also notched the vertical board for the center frame and the crosspiece for the trellis at this time. I set the depth stop on my chop saw so the blade cut half the depth of the 2” x 4” and made a series of cuts to remove the material at a point that split the distance from the top of the box (marked above) and the top of the 2” x 4”. I first trimmed the crosspiece to 88” to fit between the two end frames (8’ deck board length less two 2” x 4” and one deck board thickness). Then, I notched it in the center to mate with the previous board so that all of the trellis frames would provide an even surface to mount onto.

Image left: Joining the frame. Image right: Mounting the top spreader.

To finish my cutting, I made four vertical braces with the offcuts from the frames that could be screwed to the front and back walls, giving the boards attachment points at every 2’. In total I used eight 2” x 4”: three full-length vertical supports for the trellis, a trimmed crosspiece for the trellis, a full-length top piece for the trellis and three cut to make the shorter frame and brace pieces.

I kept my worktable out for assembling the frames. I set the bottom spreaders 1/2" above the ground using a scrap piece of wood as a spacer so there would be a little wiggle room in seating the completed unit against the ground. In joining the 2” x 4” for the frame, I used 3” long screws.

I turned the top spreaders for the ends on edge so they would each be against the outer walls. For the center frame, I mounted the top spreader horizontally. Originally I put it in flush to the top as seen in this photo but before final assembly, I lowered it 4” so it was below the soil when the box is filled and didn’t visually bisect the box.

Mounting the 2’ long deck boards onto the two end frames

I mounted the 2’ long deck boards onto the two end frames, working from the bottom up. I staggered the boards on the corners and pre-drilled the deck boards. Make sure the offsets of the boards on your two end frames are opposite each other (in right wall shown below, the bottom board overhangs to the front so on the left wall, the bottom board overhangs to the back). I was lucky to have two drills. I used one for drilling pilot holes and one for driving the screws so I could quickly change back and forth between the two tasks. For mounting the boards, I used 2” long screws.

Attaching the bottom full-length deck boards on the front and back.

I moved all the parts closer to their final destination and attached the bottom full-length deck boards on the front and back. Having a flat deck nearby to work on and end pieces that were already solid made it quite easy to get things assembled square. At this stage, however, a second set of hands is advisable. Once you have a few boards on, you can drop the center frame in place and use the notched crosspiece to help align further. It is a good idea to use a level and square to ensure you are screwing in the center frame and crosspiece level.

Image left: The garden bed ready to be put into place. Image right: The completed garden bed.

Once I had attached all the frames, the box was solid enough to move without the full front and back wall on. We laid it flat on the ground for a few minutes to screw the trellis and top plate on, and continued with screwing on all the backboards so it was ready to slide in next to the fence.

I chose to mount the trellis the full height, but if you wanted to stick with just one 4’ x 8’ sheet, you could have the trellis at the top with a gap between the garden and the trellis. If you wanted a fancier look, you could frame in the top of the box so it has a ledge. You can see we had finished attaching all the boards to the frames (screwed from the outside), as well as the extra braces (screwed from the inside).

The completed and planted garden bed

To prepare the ground, we removed the grass and ensured the length of the bed sloped gently away from the house (1/4” drop per foot recommended). Drainage in the area is adequate, so we laid weed barrier directly on the dirt without placing down any crushed stone. We stapled plastic barrier to the inside of the box to help prevent rot, and put a few inches of leaves from last fall in the bottom of the bed where they would continue to compost and feed the plants.

We filled the box with 30 x 25L bags of garden soil and planted. Now to sit back and enjoy the view and watch the plants grow.

Text and photos by Kristen Purpura

Kristen Purpura grew up in a family where a vegetable garden was a part of every summer. She was often recruited as a helper in do-it-yourself home-improvement projects. She has found working with her hands to be relaxing and rewarding, both as a homeowner and in expressing her creativity when chip carving or whittling.

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