Making and Planting a Windowbox
Tip for Success
If you think the wood might split, drill holes using a bit one size smaller than the screw. Partially screw in a number of screws, accurately align, and then screw home in quick succession.
Choose a piece of board that is long enough for cutting into two sides, two ends, and a base. Here we used board 6 inches wide x 1 inch deep. Mark out the two sides, two ends, and the base.
Double check your measurements — the ends must be the timber width squared (here, 6 x 6 inches) and the base 2 inches shorter than the sides. To create a neat cut, support both ends of the timber when sawing.
Using 2-inch self-tapping screws, attach one side piece to an end (two screws should be sufficient), taking care not to mix up the sides and base. If using an electric drill, be careful not to use too high a torque or speed.
To ensure the base is the right length, place the box on its side and position the base section on the edge of the side piece. There should be 1 inch of side showing at the other end. If not, mark with a pencil, cut to fit and realign.
Fasten the first side to the other end piece, again with two screws. Turn over, side-face down (as shown here), and attach the remaining side to each end—you may need to gently move the ends so that they line up precisely.
Insert the base section into the almost completed planter. Some jiggling may be needed, but if it does not fit, adjust the base as in Step 4. Carefully drill and fix the sides to the base with screws at 6- to 8-inch spacing.
Cut two battens to size to fit your box. These will not be visible, but do need to be about 1/2 inch thick. Invert the box and attach with screws or nails, taking care that they do not protrude into the inside of the windowbox.
Good drainage is essential for healthy herbs. With the box still inverted, drill a 1/2-inch hole in the base every 4 inches or so, making sure that you don’t drill into your work surface.
Check that you have sufficient copper anti-slug tape to go all the way around your planter along with a 3/4-inch overlap. Peel off the adhesive backing in stages and fix to the lower part of the box by gently pressing the tape.
For a more permanent slug barrier, nail the tape to the box using 1/2-inch roofing nails at 2 to 4 inch intervals making sure that the tape join is securely nailed. This is fiddly so watch your fingers.
Fill your planter with a top-quality compost and plant with a range of well-spaced young herbs. Fill gaps with salad leaves like lettuce or chard, taking care to ensure that no foliage creates a bridge over the copper barrier for slugs.