A homemade flower box in a window, on a balcony or patio or even in a garden is an attractive alternative to buying planters in a garden store. You can decorate a homemade planter to your taste or let the kids decorate it to give them a way to participate in gardening. You can build a planter box out of new lumber, or salvage lumber that would otherwise be thrown away and keep this useful material out of a landfill.
Lay the materials out so you can see how they will go together. The three long boards will be the front, bottom and back of the flower box. The two short boards will be the sides, and the 1-inch by 1-inch pieces will fit into the inside corners.
Glue a 1-inch by 1-inch post to the edge of one of the long boards. The post should be flush against the side and bottom edges of the board. Glue another post to the other edge of the board, and glue the other two posts to the edges of another long board. Clamp the posts to the boards and let the glue set for a couple of hours.
Drill three evenly spaced pilot holes into the long boards along the edges where the posts are, and put in three screws.
Place one of the short boards against the long board to make a corner. The edge of the short board should be flush with the edge of the long board. Have a helper hold the two boards together. Make three evenly spaced pilot holes in the short board along the edge where the post is. Screw the short board into the post.
Repeat step 4 to attach the other short board to the other end of the long board, and then attach the other long board to the short boards in the same manner. You should now have a box that is open on the top and bottom.
Drill 8 to 10 small drainage holes in the bottom of the remaining long board. Lay it on the box and drill pilot holes in each corner. The holes should be even with the posts on the inside of the flower box. Use screws to attach the bottom to the box.
Lay a piece of landscaping fabric on the bottom of the box to keep soil from falling out of the drainage holes if you plan to put soil directly into the box. You can also fill the box with potted plants.
Paint or stain the outside of the box as desired.