How to Make Window Boxes for Flowers

Measure the window the box will sit under. Measure a piece of 1inch by 8 inch umber to make two sides that are each 35 inches by 8 inches. Cut the lumber with a table saw.

Create the bottom of the box. Cut a piece of 1 by 8 inch lumber to 35 inches by 7 inches.

Cut out the ends of the box. Cut the 1 by 8 inch lumber into two 7 by 8-inch end pieces.

Assemble the boxes sides. Match up an end piece to a side piece to create an L-shape. Hold the pieces in the L-shape with a clamp. Drill three pilot holes into the edge of the end piece with a drill. Drive three 3-inch deck screws into the pilot holes to secure the end piece to the side piece. Match the other side piece up to the opposite side of the end piece to create a U-shape. Repeat the attachments at the remaining corners.

Create the bottom of the box. Lay the bottom piece on top of the rectangle. Drill pilot holes every ¾ inch around the edges of the bottom piece so the drill bit drills into the tops of the side and end pieces. Attach the bottom to the sides and ends with 3-inch deck screws. Drill drainage holes into the center of the bottom piece every 2 inches.

Sand the window box with sandpaper to prevent splinters. Paint or stain the window box with an exterior wood paint or deck stain.

Attach metal window box brackets under the window. Mark under the window the location of the 35 by 8 inch window box. Set the brackets under the window so they will set under the box with one in the center and one on each end so that they will be 2 inches from the ends of the box. Mark the location of the bracket holes. Drill pilot holes into your home's facade. Use a masonry bit on the drill if drilling into brick, stucco, stone or other masonry facade. Secure the brackets under the window with 2 ½ inch deck screws drilled into the pilot holes. Depending on your bracket style you will needed four to eight 2 1/2 inch deck screws.

Set the window box on top of the metal brackets. Add a layer of pebbles to the bottom of the box for drainage. Set a window box liner into the box. Fill with soil and flowers.