My old garden boxes were falling apart; they’d been made from 3/4″ cedar boards that were woefully unable to withstand the abuses of the elements.
The size and location of the old boxes was good, though. There were three 4′ x 4′ boxes, and one 4′ by 8′ box (really, two sub-boxes). 4′ wide is a good size; you can bend over to weed and reach plants easily, and also lumber tends to come in 4′ increments. I already had pretty good, loose soil in place.
Also, it had worked well having a built-in trellis for climbing plants like peas and beans. These were positioned on the southwest edge of the boxes so that, in summer when they were covered in a wall of greenery, they wouldn’t shade out the rest of the box.
The last thing that had worked decently well was the strip of copper tape around the perimeter of the box. Slugs and snails don’t like to touch copper. However, the tape had frayed at parts; and as the boards separated, slugs were now able to creep between the cracks in the boards.
Fortunately, removing the old boxes was easy because the wood was in such terrible condition.
My plan was to replace the old boxes in-place with new boxes constructed out of sturdier 2×12 lumber; and with sturdier 4×4 posts in the northwest side for a new trellis. I’d use lag screws to stitch things together (bolts would have been stronger and preferable, but would have taken a bit more effort).
I would combine 4′ lengths of 2×12 boards such that, for each board, one end would cap another board; and the other end would be capped. This gives a square shape that’s the size of a 4′ board plus the the width of a 2×12 (because 2x12s are actually 1 3/4″ wide, the total width is 49 3/4″).
In terms of lumber, I decided to use pressure treated fir. Cedar, which is naturally rot-resistant and good-looking, would have been preferable; but it’s significantly more expensive. Pressure-treating helps prevent rot; while I had some reservations about the chemicals used, the lumber yard I use (Dunn lumber) advertises that these boards are safe for people, pets, and plants.
I decided it would be most economical to buy 8′ lengths of 2×12, and cut them in half to give two 4′ lengths. (Also, note that pressure treated lumber is quite heavy; 12′ would have worked too, but is an awkward size and mass to maneuver).
Because the pressure treated chemicals are only on the outside the wood, when you cut pressure treated lumber, you should coat the end of the cut with chemicals to preserve the wood. Those chemicals are not to be trusted, and so I would have to be careful to have the cut ends pointing out, away from my garden.
Now I had a big pile of 4′ lengths of 2×12 boards, each with one cut end which had been treated with wood preservative. After it had dried, it was time to assemble them into boxes. First, I combined pairs into “L”s, using two 3 1/2 zinc lag screws and zinc washers at for each pair of boards.
These L-shaped boards were then positioned around the garden beds, and combined to make squares. On the northwest side, I also bolted in two 6′ tall 4×4 vertical posts.
I cut the mesh with a bolt cutter. I wanted to squeeze the mesh into holes cut into the 4x4s, so the mesh was cut to be a bit wider than 4′. I drilled holes in the 4×4 posts which were 6″ apart, and jammed the mesh in. This turned out to be a pretty awkward project; you want to wear gloves, it’s easy to get poked!At last, the project was done! I put horizontal wooden 2x4s (cedar) at the top of the trellis. As a finish touch, I slid glass caps on the top of the 4x4s to add a touch of flair, and also to prevent water from soaking into the top of the lumber.
Fast forward a few months, and you can see that the garden is booming!