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
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
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
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
Nail the front, back and sides of the box onto the base.
Step 5: Make Drainage Holes
Step 6: Add Corner Bracing
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 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
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
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
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.