Let your do-it-yourself talents blossom — build a flower box
There are several ways to support a flower box, the most common being metal brackets that are screwed to the wall. The challenge when using a bracket is to make sure that the screws go into solid lumber. The only problem with this approach is that the placement of the brackets might not be centered under the flower box.
Centering brackets on a masonry wall is easy, and it’s easy to anchor them for solid support. However, many houses have wood or vinyl siding, with the wall studs undoubtedly off-center.
This is why I usually don’t use brackets but choose instead to use hidden French cleats. A French cleat is a time-tested method to secure pictures, mirrors, mantles and even window boxes to a wall surface.
The French cleat is a two-piece connection system where the piece of wood or metal that’s attached to the window box interlocks with the mating piece that’s attached to the wall. The best part is that, once installed, the window box will appear to be floating in mid-air with no visible support.
It’s easiest to use lumber to create a French cleat. I highly recommend using treated lumber in your case, since the wood will be subjected to water. You don’t want the French cleat to rot and then fail, causing the window box to crash to the ground.
The French cleat can be made from three-quarter-inch-thick material. You need a piece of lumber that’s about 3 inches wide and as long as the window box.
The magic happens when you cut the single piece of lumber into two pieces along its length. You need either a circular hand saw or, better yet, a table saw with the blade set at a 45-degree angle.
By splitting the piece of wood down the middle with the saw set at the angle, you create two pieces of lumber that look identical— but one actually interlocks with the other when mated together. This is what will hold the window box to the wall.
The piece of lumber that attaches to the window box is screwed to the box so that the angled cut points to the ground, and the long tip of the cut is not touching the back of the window box. The flat or square edge of this piece is usually flush with the top of the rear of the window box.
The other piece of lumber gets screwed to the wall of the house, with the angled cut pointing up to the sky and the long point not touching the wall
When you bring the window box over to the wall and allow the two pieces of lumber to interlock, the box will be securely attached to the wall. The only tricky measuring that you have to do is to calculate how far below the bottom of the window sill (or window frame) to attach the piece to the house.
Typically, the top of the window box, once installed, is an inch or so below the window sill or the outer frame of the window. It’s easy to do themath to see where the bottom of the house piece needs to be in order for the box to be at the right height. If you started with a piece of lumber 3 inches wide, the square bottom of the house piece needs to be 4 inches below the bottom of the window sill or window frame.
The pieces of treated lumber that are screwed to the house as well as to the window box need to be attached using galvanized or stainless-steel fasteners. These will not rust.
When you attach the one half of the cleat to the house wall, be sure it’s parallel with the bottom of the window sill or the window frame. You’ll be tempted to use a level for this task, but that could be a mistake. You don’t want the window box level if the bottomof the window itself is not level (after you’re done, it will look like you made a mistake).
You might have to install one or two three-quarter-inch blocks of wood on the lower rear corners of the window box to ensure that the box doesn’t tip. The French cleat will hold the back of the window box away from the wall, so the blocks ensure that the top of the box is level fromfront to back. These blocks will not be seen when you look straight on at the box.
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Window boxes full of flowers can be used under windows or to add color to deck railings.