Our three designs are all based on a simple bottomless plywood box that you can dress up as you like. Use our suggested designs, or strike out on your own.
Experienced woodworkers will find these boxes easy to build from the diagrams presented on the following pages. If you're less adept, a professional should be able to create them for you for a reasonable cost.
1. Begin by measuring the width of the window. Most window boxes look best stretching between the outside edges of the window trim.
2. Purchase a plastic tray the same length as the width of the window (or two trays placed end to end). Hold tray(s) up to window to ensure accuracy.
3. Build a simple box from 3/4-inch exterior plywood to hold the tray. (If box is a little too large, add 1 x 2s to bottom of box, front and back, to hold the base of the tray.)
4. Add supports, using cedar or other rot-resistant wood, or use heavy-duty metal brackets to attach to your house.
5. Alternatively, predrill three screw holes in back of box. Drill three matching holes into sill plate under the window. Put sealant into holes to keep water from seeping into the wall. Hang box securely using 3-inch galvanized deck screws, or masonry anchors on brick.
6. To plant the box, punch out the tray's drainage holes, add potting soil to within 1 inch of the tray's lip, and select plants with similar light and water needs.