A window planter provides apartment dwellers, office workers and homeowners a chance to have their own container garden where they can grow plants and flowers of their choice. These window planters add color outdoors, sprucing up the windows with colorful tall and cascading flowers and plants. Although window planters are available in garden supply and home department stores, you can make one yourself at half the price. You do not need prior skill or experience to build this simple rectangular window planter.
Decide the length, width and depth of your window planter. Opt for two medium planters in place of a very long one, and keep the width up to 3 feet. A height of 7 to 9 inches provides sufficient room for the root system to grow and develop.
Use a handsaw to cut the wooden boards to size, or purchase them pre-cut from a hardware store. Select oak, pine, teak, redwood or any other type of wood for your planter, keeping it within your budget range. You need five boards for a window planter: one base board, two same-size short sides, and two identical long boards for the front and back.
Drill 1-inch drainage holes into your base piece, 5 to 8 inches apart. Sand both sides of the piece to remove any sharp edges around the holes.
Hold the front of the planter and place a short side flush against it on your worktable. Position them so their lower edges rest firmly on the surface and their tops are at the same level. Make sure the joint is flush and even before drilling two galvanized woodscrews to attach them together. Check the L-shaped structure to make sure the joint is secure, and drill another woodscrew in the center for added stability.
Assemble the planters back piece to the other short side the same way.
Place both the structures together in such a way that the short side of one is flush against the long board of the other. Hold them firmly against one another so the two joints are flush, and drill galvanized woodscrews into them. You now have a rectangular planter that does not have a base.
Turn the planter around so its base cavity faces up, and carefully lower the base piece over the edges. Secure it in place by drilling four woodscrews along each long side, and two along the short sides.
Sand the surface of the planter box to give it a smooth finish, including the inner corners and edges. Paint it a bright color so it stands out, or a coat of clear paint to protect it from natural elements.