Cut the 1x6 into three 2-foot lengths, and two 6 5/8" lengths. (Your local Dunn Lumber will do this for you!) We used the fencing cedar because it's thinner than a normal 1x6. The thickness of the 1x6 varies between 5/8" and ¾", so if you're cutting it at home and you want it to be very exact, you'll want to measure specifically for your pieces.
Drill five holes with a 3/8" drill bit 4 inches apart in the center of one of the 2' lengths. This will be the bottom of your flower box.
On another of the two-foot pieces measure an inch from the edge on either side. Line up the measuring tape along your two marks. With a pencil, mark every four inches and ½" in from each edge. You should end up with 7 marks. Repeat this step on the remaining two-foot length. You now have a bottom and two sides.
On your end piece, measure in half an inch from the short edge. Line up your tape again, and mark every inch along this line. You should end up with 5 marks with one side about a 1/2 “ from the edge. This is your top edge. Repeat measurements on opposite side.
Now, along the bottom edge of the piece you're going to make three marks an inch from the bottom and 1 and 3/8" from each other and the marks on the sides. We weren't too exact about where we measured, but we did the work to figure out the precise measurements so that you can be exact. Repeat steps on the other end piece.
You've made all your marks, now you can drill them with the small drill bit. Your drill bit should be a hair smaller than the nails that you're using. That way the nails have something to grip to when you put them in.
Next take your hammer, nails, and your two-foot length with all the little holes. Lightly tap your nails so they just poke out the other side.
Stack your bottom piece on top of the left over 1x6 (you should have about 10"). This will make the bottom of the flower box inset so that it has room to drain. Now take the piece with the nails and holding it perpendicular to the table and line it up with the other pieces. Firmly press the nails into the edge of top board, and start tapping down the nails. Once you've got one nailed down you can turn the whole thing sideways to nail the rest. Repeat with the other side.
Now repeat with the bottom edge of the end pieces. Finish up by nailing the end and side pieces together through the predrilled holes. Be careful to be really straight while hammering these nails.
Lift the flower box off of the extra board, and you are all done! You can leave your flower box as is, or you can add some paint or stain. It'd make a great gift for mom, dad, or anyone else who loves summertime blooms!