Using the appropriate perimeter stake line, mark off the corners of one end of each bed by driving 5/8-inch rebar stakes into the ground next to the string. Using our example of 40-inch beds on 5-foot centers, the stakes should be positioned at zero, 40, 60, 100, 120, 160, 180, 220 inches and so on along the length of the string, depending on the number of beds to be constructed.
If the plot is level, stakes may be driven flush with the string, 6 inches above grade. If the plot is sloped perpendicular to the long axis of the beds, only the first corner stake of each bed (0, 60, 120, etc.) should be driven flush with the line and a carpenter's level used to level the second corner stake with the first. Orienting the stakes at a slight angle leaning away from the bed will help minimize their movement when the rubber boards are stretched.
Mark off the corners on the other end of the beds using the same procedure described previously, with one exception: don't drive stakes to their final elevation. Rather, drive them into the ground only a few inches, as they will need to be pulled up and attached to the material prior to their permanent placement. Remove the perimeter stake lines as they will be in the way when installing the plastic strips.
Next, attach one end of the plastic strips to the permanent 5/8-inch stakes by looping the material over the stakes.
Pull one of the strips of material across the plot and attach the free end to a hand winch by means of the 8-inch piece of 3/8-inch rebar and a wire sling. Applying tension to the material using the winch will ensure a nice, tight, straight border. With tension applied, make sure the strip of material rests against the temporary 5/8-inch rebar stake.
If this is done properly, the material should be standing on edge.
While under tension, remove the temporary 5/8-inch end stake, place through the loop and drive into the ground. Anchor the material to the ground using 3/8-inch stakes positioned every 18 inches. Be sure to weave the rod through the material prior to driving them into the ground. Drive the stakes to within 3 inches of the top of the material (9 inches above ground level) and stop. Care should be taken not to stretch the material too tight, as it could rip when the support stakes are woven through the mesh.
Replace the perimeter stake lines. String a line across the perimeter stake lines parallel with the strip of material. Finish driving 3/8-inch stakes to their final positions. Use the string as a gauge to ensure all the stakes are set at the proper elevation.
You have now completed a plastic mesh border. Remove the winch and repeat the procedure for other borders.
Next, line the inside surface of each border with strips of the roll roofing material. To hold the liner in place prior to filling the bed, place a shovel scoop of soil against the liner every couple of feet.
Finish construction by placing end pieces on the beds. You can fabricate end pieces out of the mesh fencing, treated lumber or, better yet, pieces of tire tread (see section on recycled auto tire bed assembly).
You are now ready to fill the beds!