I went out and bought the materials to make two 4’x4′ Square Foot Garden (SFG) boxes with raised 2’x2′ sections for deep-rooted plants (potatoes and carrots). I had to buy six 2″x6″x96″ boards, plus rust-resistant screws, weed block cloth, and hardware cloth. I also had to buy a bunch of vermiculite, peat moss, and compost.
All told, the assembly process took me about eight hours, but I’m really out of shape. My friend Sam probably could have done the whole job in half that time. I cut four of the boards in half, and the other two into quarters.
Then, as Mel suggested, I drilled three pilot holes across each board, about 3/4″ from one end. I fastened the boards together by making “L” shapes and screwing through the pilot hole board sideways into the end grain of the next board. I repeated this process all the way around until I had a box. This meant that I didn’t have to do all sorts of fancy calculating to get the measurements right. I just cut the boards into 48″ halves.
I ended up standing the boxes on end for the final join because they didn’t want to be quite flat. Pulling them together for the last bit and leaning on the top board let me hold the two together until the screws could do it. In the end, the boxes were pretty solid.
Note that I’m not using pressure treated lumber. They won’t last as long, but the boards aren’t going to leach poisons into my veggies.
Once I had the boxes assembled, I laid them out on my front lawn to get the spacing right. I did this pretty roughly because I knew that I’d need to measure more accurately once I got the bottoms on.
After figuring out about where I wanted the boxes relative to chairs and such, I began attaching weed block and hardware cloth to the bottoms of the boxes.
I laid a layer of 6′ wide weed cloth down, then I laid another layer off to the side at a right angle to the first and stapled just the edge where they met. I then nailed the hardware cloth with a few bent finishing nails (I couldn’t find my heavy-duty staple gun) along the same edge. This allowed me to pull the metal grid tight (with the bottom weed block) and affix it as I went.
Once I had the hardware cloth mesh most of the way flat, I stapled the far end of the weed block and cut the mesh with a pair of tin snips. I also flattened out the sharp nubs as best as I could with the hammer and a pair of pliers. That way I hopefully wouldn’t get any nasty cuts on my hands or tears in the weed block. I probably could have skipped the mesh, but I’ve had burrowing mammals in my yard lately and I was feeling paranoid.
Having cut and smoothed the far edge of the mesh, I carefully folded the outer layer of weed block over the edge of the mesh and nailed it down. Then I folded the flaps of the inner layer of weedblock over the sides and stapled those down. The end result was a neat little package of metal hardware cloth (chew on THAT gophers!) sandwiched between two layers of anti-weed material to help keep my virgin soil weed-free for as long as possible.
Now, I carefully positioned the boxes according to the measurements I wanted. I wanted 4′ on the back and walkway sides and 3′ in between the boxes. This would allow me plenty of walking access and would also help to keep the worst of the snow avalanches off of my boxes in winter. It also left plenty of room in my lawn for people to sit out in chairs by a firepit, even if I added more boxes to the right of those in the picture. Once everything was straight, I filled them with my soil blend.
I’ll talk more about my specific soil blend later, because there are a lot of details there as well. Suffice it to say I followed the instructions almost exactly, but I think I didn’t get enough vermiculite. My whole batch barely filled the two big boxes and about 3/4 of the small “top hat” boxes. I ended up using some leftover organic potting soil to top them off. Note the grid made of wooden lath. This is an important part of the plant management and garden planning process.
Here you can see the final shape of my two SFGs. Because I used a 10′ roll of hardware cloth, I had about 2′ left over. I made that into a little mini tent to keep birds off of my bean seed until they started to grow. I will talk about my choices of plants in another post. This one is getting long.