window boxes - Knowledgebase Question

Easton, Ma
Avatar for radsue1
Question by radsue1
April 15, 2010
do you have any tips/plans for building flower boxes? My husband wants to build two for shaded windows, thanks

Answer from NGA
April 15, 2010
I don't have plans to share with you, but I can walk you through the process. First, measure. The width of the windows determines the final length of the planter. The depth and height should be large enough to hold pots or an amount of dirt that will retain moisture for a few days. In our project it?s determined that the box should be 7" deep and 7" high to accommodate 6" flower pots. I'll use these dimensions as I walk you through the steps but feel free to change the dimensions if you want larger or smaller window boxes.

To support the weight of the box and the dirt that will fill it, use brackets. Metal brackets are fine, or you can make brackets out of scrap wood. If your siding is flat, brackets will be easy to find but if you have siding on your house, the siding will prevent the brackets from securely adjoining the house exterior. If this is the case, make a cardboard template that will help guide you in cutting the notches into your wood brackets.

The next step is to select the wood. Certain types of wood aren't suitable for this project, so make a careful selection that will balance aesthetic needs with practical ones. Pine rots easily and oak turns black when wet, so they are not good choices. Cyprus is popular in the South, and becoming more popular across the country, high oil content makes it weather-resistant. Cedar is both decay-resistant and affordable; it can be left natural or can be stained with good results and is available in smooth or rough finishes. Teak and mahogany are beautiful, but expensive.

After determining the full width of the planter, cut front and back boards to the appropriate length. After cutting the ends, trim 1" x 8" piece of lumber to 7" wide.
Mark lines with square and use a belt sander to bevel corners at a 45-degree angle to reduce splintering. Remove any additional sharp or rough areas. Repeat beveling for all corners. Smooth with sanding block.

Cut the scrap wood left over from cutting down width, and already 7" high for end pieces. These pieces are cut to 7" long. Apply glue to the slots in one of the longer pieces the front or back. Add end pieces to the slot and tap into place (Image 1). Pull remaining long pieces to the end pieces. Use bar clamps to secure all pieces during drying.

Next, measure, cut and secure the bottom piece. Measure bottom piece for snug fit. Cut to proper width and length. Apply a bead of glue inside the bottom edges of planter. Align bottom with bottom edges of front, back and side pieces. Use mallet to tap into place. Use screws to secure bottom piece to edges of side, front and back pieces.

Drill drainage holes in bottom, spacing about 12" apart, beginning about 6" from each end.

After the box planter is assembled, cut brackets to support the weight of the planter, dirt and plants and secure to the home?s exterior. The brackets can be cut in any design desired, but the cardboard templates you made earlier can be used to cut the notches necessary for the brackets to fit flush with the exterior surface. The color of stain applied to the window-box planter and brackets can be chosen to match the existing house trim. Begin by tracing around cardboard template onto wood after determining the height and width for the brackets. Use a handsaw to cut bracket curve and notches. Remove any marks with a sander. Finally, countersink holes on each bracket's edge for screws to be added during installation. Repeat process to complete two additional brackets.

Once the planter is completed, a finish can be chosen to protect the wood and add color if desired. Plain wood can turn gray, dry out and rot without protection, so stain or paint is vital to this project's longevity. Although paint initially provides good protection and good coverage, it can later peel ? it's an option with a short life.

Position each bracket where needed to provide good support. One at each end and if your planter is long, add a bracket in the middle, as well. Use a level to make sure the top of each bracket is correctly aligned. Drill 3" screws into countersunk holes to attach bracket to house exterior. Use wooden buttons to hide screws and fill holes.

Add remaining brackets and place box atop brackets. Add potting soil and plants or potted plants as desired.

Enjoy your new planter boxes!

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