This year, I wanted to make good on a long-standing promise to set the family up with a garden. I’ve looked at raised bed gardening because I don’t know too much about the quality of soil in our rather urban suburb. But like many people with bad backs, when I see people gardening (raised bed or not), my first thought is, “Aren’t farmer’s markets great?”
We visited some good friends in Sonoma a few years back and they had built some raised garden beds unlike any we had seen before. These were roughly 3.5–4 feet high and seemed like a brilliant way to improve the ergonomics of gardening. But I have some big ideas for the backyard over the next few years and I don’t want to commit to large, immovable containers of soil. I looked into commercially available elevated garden beds but I find them ugly, find them expensive, and like all woodworkers, I immediately resent the very notion of purchasing something I know I can make.
Spoiler alert! The result, already sprouting some tomatoes.
I had a free Sunday a few weeks ago, so over morning coffee I spent a few minutes mocking up something in SketchUp. I planned on building the boxes out of 2×8 cedar boards, but while at the home center a little later I decided instead to use some nice 5/4” thick cedar I found in the stacks. This stock was much nicer, had square edges, and would obviously yield much lighter garden boxes. The home center was completely out of the 8” wide boards they normally stocks in this thickness and had only 6” widths that day. So after recalculating the amount of lumber I needed, I went home with a few 10’ 4x4s and 2x8s and a bunch of 8’ boards of the 5/4 stuff.
As some of you know from earlier posts, my woodshop is in the basement. But the shop’s Scenic Corrugated Metal Window Well, located next to the driveway, provides a very convenient way to feed boards off the top of my car directly into my shop. The end result looks like an Ent vomited over my lathe.
I designed the boxes to use dimensional lumber as-is, so processing the lumber involved a lot of time at the miter saw. In no time at all, I had most of the pieces cut to size and my shop smelled like a gerbil cage (and for the record, still does a few weeks later).
I ran the posts into a spiral bit on the router table a few times each to create the stopped dado in which the sides sit. Some of the commercial elevated garden boxes use a sliding dovetail, but wanting to finish these boxes before 2019, I decided to just use a straight dado to keep things simple. Cedar posts from a home center are typically not very dry, so after cutting the dado, the chips are packed very densely.
I realized that because the wood was so wet, the dado’s dimension was going to change significantly during the project build, so I cut them a tad larger than the boards they would fit. Also, immediately after cutting dados in a bed’s worth of posts, I clamped them together with boards from the bed so that as they shrunk, they wouldn’t distort too much.
That was a good call—the next evening, when it came time to assemble the beds, I had to pound those boards out with a mallet, but the dados were still straight.
After cleaning up the stopped end of the dados with a chisel, the only other lumber prep was cutting the curves. For this, I made a template in some 1/2” ply I found in the garage attic. The curves differ a little between long and short sides of the box, so I used one side of the ply for the long curve and another for the short curve. I drew out the curves with a flexible stick, screwed them into the back of each side’s bottom board, cut close on the bandsaw, then used a pattern routing bit on the router table to finish up.
This was by far the most time consuming part of the stock preparation, and even this only took a little over 80 min. It did make me very grateful for the fact that my basement shop is built well enough that no one hears me pattern routing and running the dust collector at 1am.
Assembly went very quickly. I used one Sipo Domino in each of the long side boards to keep them roughly aligned and to provide a little lateral reinforcement from the soil in the beds (which would push outward).
This being a project made of cedar, intended to remain outdoors year-round, and with the massive climate changes in the Midwest, I designed the boxes with a lot of room for the wood to move in whatever way they wanted. Also, I want to be able to replace boards easily. So I used no glue and in the main box, only the bottom boards are screwed into the posts (from the back of the post into the “tenon” bit that fits into the dado). The rest of the boards which comprise the box sides just sit on top of the bottom one, the top board sitting a little proud of the post.
That bump is intentional—it sits inside a dado underneath the seating ledge, which is taller than it needs to be to allow for the side boards to expand. Time will tell if this works adequately but I’m reasonably sure it’ll be fine. Between the dominos and this dado, the sides should sit straight enough. This photo shows the ledge dados a little better.
The 2×6 ledges (also cedar) were then mitered to length and screwed into the top of the posts. Bottom boards just sit on top of two runners on the inside of the chest, with one 2×2 support screwed across the center of the runners to keep things together. The bottom boards on either end of the box have a little notch to accommodate the corner posts, and these were cut with a handsaw. To make the bottom of the boxes a little easier to understand, here’s a SketchUp diagram:
Runners and x-support (all 2×2 lumber) = brown; notched end boards (the 5/4 thick stuff also used for the box sides) = blue
Before long, I was done with one box, which I then pushed out of the shop to make room to assemble more of them.
I had started this project with the intention of building only two boxes, but I made no cutting mistakes while dimensioning lumber. I had enough left over to build a third box after purchasing just a few more boards, and enough after that to build a little step stool for Anya. The step stool features some handles that prevent her from accidentally stepping off the side of the stool and which also prevent me from having to bend over to pick the stool up.
This was a great project. It took probably 20 minutes to design, and not including lumber procurement, all three boxes and the stool took maybe 15 hours total to build. One comparably-sized elevated garden box made out of cedar costs about $300, isn’t really at the right height, has no seating ledge, and looks like a glorified sand table. The lumber for all three of these boxes cost perhaps $450, and I didn’t shop around. While I’m sure they won’t last forever, with a repair or two here and there, we should get years of enjoyment out of these.
Which is great, because with enough sun and water, you can grow just about anything:
It’s a slightly cleaned up version of the original drawings I did; I’ve sized the pieces to their final dimensions including using actual (not nominal) dimensions for the lumber. I didn’t add any measurements largely because I figure anyone who builds this will use this as a guide and size the box to their liking. Let me know if you build one and how it turned out.