Growing plants in a container or planting box allows you grow where you otherwise cannot have a garden, or to create a smaller garden within a larger one. Though most plants can grow in containers such as buckets, pots or barrels, you can make your own planting box from easily accessible materials. Building your own allows you to choose the size and shape of your planting box.
Measure the lengths of the cedar boards, marking the measurements with a pencil once you have decided how big your planter box will be. You may use whatever thickness of boards you like, though at least 1/2 inch is preferable. If you want a planter that can sit beneath a window and grow small flowers, 8 by 24 inches may be a good size. For this you will need three cedar boards that are 8 by 24 inches, and two that are 8 by 8 inches for the ends.
Cut the boards with a handsaw where you marked the measurements.
Drill at least five drainage holes along the length of one of the 8 by 24 inch boards with your hand drill. This will be the bottom of the planter box.
Place the two other long boards on top of the bottom board, matching the sides with the correct lengths. These will be the front and back. Turn the project over so the bottom board (with drainage holes) is resting on top of the other two. Drill screws into the front and back boards from the bottom of the planter box. Drill three evenly spaced screws into the edge of each the front and back boards through the bottom board.
Turn the project right side up again. Your side boards should be secured now from the screws you drilled into the bottom. Drill your 8 by 8 inch end boards onto each end with one screw at each corner, using four screws for each.