These scrap wood window planter boxes have two big steel hooks on the back of them that hang onto the bars on some of my windows. I figured why not take advantage of the ugly, but perhaps necessary bars that are all already securely mounted onto the window frame, and brighten them up a bit with a hand built unique window box.
I made two boxes, one large one for our kitchen window that has a mixed variety of nasturtiums growing in it. The other box is a bit narrower - sized more appropriately for the smaller adjacent window. That box is growing a climbing plant called Asarina Scandens "Joan Lorraine" with purple flowers that's known to be a good climber. It's already starting to creep up the bars and give us a bit more 'natural' privacy on our bathroom window.
This project is very easy and can be completed in a matter of hours with very affordable materials.
Step 1: Bang on Steel
I cut two 12" lengths of 1" x 1/8" flat steel bar on the horizontal bandsaw (hacksaw or angle grinder also works just fine). I then proceeded to hammer on the steel bars with a small sledge in a vice to create some very crude but strong hooks.
Make a 90 degree bend around 2" in from one end. Expose another inch or two of steel in the vice and make another 90 degree bend.
The hook is now formed. Repeat for all lengths of steel.
Step 2: Drill Holes
Take the steel hooks over to the drill press and drill two holes on the long end of the hook around 6" apart. Make sure one is close to the bottom of the book.
Use a lubricant (bike chain lube works just fine) while drilling.
Remember to wear eye protection to protect yourself from the little bits that may fly off the drill bit.
Step 3: Measure Box Dimensions Onto Wood
I'm using a scrap piece of pressure treated 2" x 6" for the bottom of the box and cheap redwood fence panels for the sides. Everything can be found at your local home depot or lumber yard.
If I were eating any of the plants from these boxes I'd stay away from using pressure treated materials. Even though they no longer are pressure treated with arsenic, I still prefer not to eat the stuff. Since these boxes will only hold decorative flowers, I let it slide.
I measured my window frame and built the boxes to suit the different sizes - one long box, and one short.
Mark the length of the box upon the base and make the cut on the chop saw.
The front and back panels were cut just a bit longer so that they'd extend past the sides.
Step 4: Assemble the Box
Using a brad nailer I assembled the planter box.
Nail the front, back and sides of the box onto the base.
Step 5: Make Drainage Holes
Using a large (3/8" is a good start) drill bit, drill holes all along the bottom of the boxes for drainage. Doesn't need to be fancy, just has to allow water to drain through.
Step 6: Add Corner Bracing
I cut a few pieces of 1 1/2" square scrap to length and nailed them into the corners of the box for strength. This material isn't pressure treated or rot resistant like redwood, but it should still last a while.
At this point, put down the brad nailer and grab the drill. Drive screws through all panels into the base and corner braces to add additional strength. Galvanized brads won't last long, and screws provide much more holding power.
Use stainless screws if you want the box to last a long time. I rent in California - this box is not meant to last a lifetime and so I take certain liberties with the outdoor screws I use. Zinc if possible, gold drywall screws in a pinch, and drywall screws when I can't find anything else lying around.
Step 7: Cut Scrap Wood Slats
I gave these window boxes the same treatment as my 55 Gallon Drum Planters and covered the outside with scrap offcuts of thin material that I had been collecting.
I cut the wood scraps to similar length on the chop saw and assembled them in a randomized pattern on the front and sides of the box...no need to do the back, no one can see that side.
Step 8: Nail in Place and Finish With Outdoor Varnish
Use a brad nailer to secure the facing material in place onto the redwood backer.
On one box the scraps were lined up to be perfectly even and the top. On the other we cut the scraps to different lengths and went with a more random pattern.
Do whatever you think looks good.
With the box fully assembled give everything a coat of your favorite outdoor varnish. I prefer a waterbase varnish since it's easier to clean up and has a gentle satin finish.
Step 9: Screw Metal Hooks Onto Planter Box
Using some beefy screws, attach the metal hooks onto the back of the planter box.
Be sure that the bottom screw grabs the base of the box. If the upper screw doesn't grab firmly in your thin redwood back panel, place a piece of scrap right in that spot to provide more material for the screw to grab.
Remember to drill pilot holes for your screws so you don't crack the thin redwood back panel.
Step 10: Hang From Bars on Window and Plant
The planter boxes simply hook onto the bars on my window. If you don't have bars on your windows you can of course screw the brackets onto your window ledge or figure out some other conventional way to mount window planter boxes.
Depending on how your bars are mounted, you may need to block out some space between the bottom of the planter box and the house so that the boxes hang level. Two quick cuts of a 2 x 4 do the job - they just get slid into place behind the box and held in place by the weight of the box.
Fill with soil and plant with something beautiful.