A window plant box provides you the opportunity to enjoy vibrant color and a lovely aroma year-round. It not only enhances the look and appeal of the exterior of your house or apartment but also will be enjoyed by people on the street. You can grow herbs, plants or flowers in different boxes placed outside each window of your house that can be both decorative and functional. Use your personal taste to grow annuals, perennials and biennials that you can enjoy.
Measure the width of the window so that you can decide the window box length, width and depth. Keep the width of the window box 2 inches narrower than that of the window to provide sufficient space for cascading plants. Jot the measurements down on paper.
Use the measurements as a guide and purchase precut boards of rot-resistant pressure-treated lumber from your local hardware store. Make sure the wood is at least 1-1/2 inches thick to support the weight of the soil and plants. Rub all edges of each board with sandpaper to remove any splinters and make them smooth.
Cut the boards to size yourself with a circular saw if you do not want to spend the money on precut boards. Measure and cut two lengths of 1-1/2-inch-thick wood for the front and back of the window box and another two lengths for both sides. For the base of the window box, measure and cut a piece as long as the front and back sides but as wide as the sides. As with precut boards, rub all edges of each piece with sandpaper until smooth.
Drill six to eight 1/2-inch holes in the base piece for drainage. Rub the surface of the holes with sandpaper to make them smooth, and then turn the board over and rub the other side.
Put on protective eyeglasses and earplugs. Place the base piece on a flat, even surface such as a worktable, and hold the back piece flush against it. Make sure both pieces are level with each other before securing them together by drilling holes for 1-inch galvanized wood screws, one at the top and the other at the bottom. Screw in the screws.
Hold one of the sidepieces against the box, making sure it is flush against the base and back before screwing it in place. Repeat the procedure to attach the other sidepiece to the framework before finally progressing to the front piece. Check to see whether the box is sturdy and does not move; when it is, screw in another wood screw on each side.