Step 1: Trim the Support Posts

To construct the flower box, trim off the original support posts using a reciprocating saw.

Step 2: Make and Assemble Flower Box Walls

Lay out three more cut 4 x 4's to serve as support posts for the box (Image 1). Using two of these posts, fashion one wall of the flower box by attaching several 2" x 6" boards (Image 2).

After positioning the wall, continue by screwing an adjacent wallboard spanning to the original support post (Image 3). With the two walls connected, toenail a screw to set the wall post to the deck (Image 4).

Fashion a similar wall for the opposite end of the box, attaching the posts with toenail screws. With the four posts set to the deck, continue to attach wallboards — building up the box (Image 5).

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Step 3: Make a Flower Shelf

Add a flower shelf, called a false bottom, inside the box. Start by screwing in 2" x 6" crossbeams to the box's support posts (Image 1). With the crossbeams secured, screw in sized 2" x 6" planks to form the shelf (Image 2). Then drill holes through the planks for water drainage (Image 3).

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Step 4: Construct a Top Cap

Complete the flower box by constructing a top cap consisting of four miter-cut 2" x 6" boards. After cutting the boards to size, attach them with several screws.

Step 5:

To put the finishing touches on the deck, prepare for staining by scuffing the wood with a hand sander (Image 1). After letting the deck cure over a weekend, add a clear, protective stain with a roller for the flat surfaces, and then use a brush on the smaller areas (Image 2).

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