I have a South-facing wall that was just crying out for tomato planters. Since the wall is along a fairly narrow walkway and I couldn’t find pre-manufactured planters of the right dimensions, I decided to build my own.
I chose yellow cedar slats, because I love the way cedar smells, it stands up well to weather, and since my hot tub is made of yellow cedar, I would have consistency of design. You could use any kind of wood, but make sure it’s not treated with any chemicals that will leach into your soil and edible plants.
Because my walkway slopes a little, I cut the legs to different lengths so the top of the planter remains level. Just for fun, I also used a long level, some string, a trigonometry equation and a compound miter saw to cut the bottoms of the legs at the exact same angle as the walkway. I used redwood 2x4s for the legs.
Once my legs and slats were cut to size, I squared off each long side by nailing 2 slats to 2 legs. I let the slats overhang each side, so that later when I nail the short-side slats, the two sides will form a butt joint at the corner.
With the rails in place, I created the bottom platform out of 1×6 redwood planks that sit right on top of the rails. There are plenty of gaps for water to exit between the planks. The 2×4 legs and rails, and the 1×6 planks, act together to form a rigid frame for the whole structure.
I made a second planter, added a drip irrigation line, and a couple of trellises — one made from some electrical conduit I had lying around, and one made from some castoff closet rods. I planted tomatoes in the first planter, and blackberries in the second planter.
Both the tomatoes and the berries love these planters. They don’t get sun all day, but they thrive on the retained and reflected heat from the stucco wall. Each of my planters is 18″ by 6′ with about 20″ of soil depth, and based on my research you do need that 18″ of side-to-side room, and 20″ of depth, to grow berries or tomatoes. You could get by with very shallow boxes for greens or herbs.
This whole project was completed over one weekend this spring, and we have not been able to keep up with our tomato crop — I planted 3 varieties in one 6-foot planter, and I have never seen tomatoes plants grow so fast or so profusely!