Making Planter Boxes

Lay the 24-inch sized planks on the ground, 12 inches apart and parallel to one another. Set the 3 remaining planks atop these, one on each end, and one centered between them. There should be around 3 inches space between them.

Nail the 3 planks down, putting four nails in a square over each bottom plank: there should be 8 nails in each of the three planks, 24 nails in total. This is the base of the planter box.

Arrange the sheets of wood into a box: make the 12-inch square sheets the ends, and the 24-inch long ones the sides. Place a line of wood glue on the corners that meet, then clamp the box together with the band clamp until the wood glue is dry.

Nail approximately 6 nails into each joint area after the glue is dry, but before taking the clamp off.

Place the base of the planter box upside down atop the wooden box so that it is flush with the sides of the box, then nail the base to the box. Now turn the whole box up the right way, so the base is now on the bottom. The planter box is almost complete.

Sand the box roughly, smoothing out any major rough areas. Dust off with a clean, dry paintbrush.

Varnish the entire box with wood varnish, then let dry completely. Use either a natural resin-based or natural oil-based varnish. Avoid polyurethane varnishes, as these can exude chemicals and deteriorate after prolonged exposure to UV light.

Line the planter box with the black plastic sheet. Poke a couple of holes into the bottom of the sheet so that the planter box will have drainage. Try to make the holes in the spaces between the planks on the bottom, to minimize water damage to the base. The plastic protects the soil and plants from any instances of chemical seepage from the wood, although this is rare.

Move the planter box to the desired location, then fill it with potting mix. Trim off any excess black plastic that is showing above the rim of the planter box.