The boxes were constructed by a friend of the client. He grew up laying forms for concrete which is not so different from retaining soil.
Our boxes are of 2″x10″ treated lumber. There is a plastic membrane separating the soil and wood.
The box must be strong in two ways. It must stay in place horizontally and vertically.
The lumber must retain the soil. The strength for this is provided by using strong lumber that will not bend, by driving rebar stakes along the outer edge of the lumber box, and by reinforcing the box’s corner joints with 2″x2″ wood. Our boxes are nailed together with box or decking nails (twisted) and they do not pull out. Additional retaining strength will be provided when the areas between the boxes are backfilled with gravel, and eventually, pavers.
It is very important to affix the lumber to the ground. The soil will want to creep out underneath the box, lifting the box up and causing it to fail. These boxes are held down with 2″x2″ stakes into the ground. When possible, the stake was driven in inside corners. Then the box edge was nailed to it, providing not only hold-down, but corner reinforcement.
The 2″x10″ lumber was purchased, as were the rebar stakes, however, the 2″x2″ stakes were salvaged, as was all the gravel, from nearby construction.
The first step is to bring in clean garden mix and place it at 18-24″ depth.
It is important to not drive on the soil with equipment. The skidsteer placed the soil and did minor backdragging to grade it. Hand shoveling was done to finish up the grade and fill in the corners. Boxes will be built this week to keep the soil in place.
For the first year we’re planting lots of corn, beans that climb the corn, squash, beets, tomatoes, and greens. There will be a raspberry & blackberry patch soon, bearing fruit next year. We’ll espalier some apple trees on the fence at the front of the lot.
Over this first year, we will be building trellises for climbing edibles like cucumbers, various squashes, peas, and beans. There will also be a pergola for heavier edibles like grapes.
To top it all off, we have an artist who will paint the fence with an amazing array of fun imagery!