How to Build Old-Time Outside Window-Planters

Measure across the exterior windowsill.

Measure a 1 inch-by-6 inch board to the windowsill measurement, less 2 inches, and mark the edge of the board with a pencil. Repeat twice, marking off three equal sections of the board.

Hold a carpenter’s square against the edge of the board, with the perpendicular edge of the square across the board at a pencil mark. Trace the edge of the square with a pencil. Repeat at each mark, marking three straight cutting lines across the board.

Cut the board at the marks with a hand saw or circular saw.

Select a drill bit that is the same diameter, or slightly smaller than the shank of the 1-1/2 inch screws, and fasten it to a power drill’s chuck.

Set one cut board flat on a work table with a long edge toward you and the shorter cut ends on the left and right. Stand another cut board upright on a long edge, and butt it against the front edge of the bottom board.

Drill pilot holes through the side of the upright board and into the edge of the bottom board, spacing the holes approximately 3 inches apart.

Insert 1-1/2 inch screws through the holes with a Phillips-head screwdriver, or use a Phillips bit with the power drill, fastening the two boards together.

Rotate the board assembly 180 degrees. Repeat the steps to predrill and fasten the remaining cut 1 inch-by-6 inch board to the opposite long edge of the bottom board.

Rotate the board assembly with one short, open end facing you. Measure from the left outer edge of the left upright board to the right outer edge of the right upright board.

Measure a 1 inch-by-6 inch board to that length, and mark it with a pencil. Repeat, marking off another identical length. Make straight cutting lines across the board at the marks with a carpenter’s square and pencil, then cut the boards at the lines.

Place one cut board upright against the open end of the box assembly, aligning the bottom and side edges of the board with the bottom and side edges of the box.

Drill pilot holes through the end piece and into the edges of the assembly, then insert 1 1/2-inch screws to fasten the end to the box. Repeat at the opposite end of the box.

Drill three equally spaced drain holes through the bottom of the box.

Measure the height of the box and the length of the back side of a shelf bracket. Measure along a 1 inch-by-2 inch board to the combined height of the box and length of the bracket, plus two inches. Mark the board, and cut it straight across. Repeat to make a matching board. These are cleats that fasten the box to the house.

Place the flat, back side of a shelf bracket against a cleat with the bottom of the bracket 1 inch up from the end of the cleat. Trace around the bracket onto the cleat with a pencil, then drill pilot holes through the cleat inside the traced outline. Space the holes 2 inches apart. Repeat with the other cleat.

Align a bracket with its traced outline on a cleat. Insert 1-1/2 inch screws through the pilot holes in the cleat and into the back of the brace. Repeat with the other cleat.

Set one cleat vertically against the siding under the left side of the windowsill. Butt the top edge of the cleat against the bottom of the windowsill with the top of the shelf bracket projecting out toward you. Insert one 3-inch screw through the top of the cleat and another through the bottom, fastening it to the house under the window. Add more screws through the cleat, approximately 2 inches apart. Repeat with the other cleat at the opposite end of the windowsill.

Set the box on the shelf brackets. Insert two 1-1/2 inch screws, equally spaced, through the bottom of the box and into the top of each of the shelf brackets. Insert two more screws, with the same spacing, through the back of the box and into each of the cleats.