How To Build A Flower Box

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After we moved the gazebo and deck over from the other side of the yard, we had a gap between the 2 decks. Originally, I wanted to purchase these really cool firepits for the area but after seeing the price, that was a no go. I decided that the next best thing was 2 flower boxes on either side of a step that I would make later.

What you will need to build a flower box

Before you start, read through the entire post to get an idea of how the project will come together.

I have learned that going through the entire instructions on how to build a flower box makes putting it all together much easier. I do this for every build that I am following instructions or a plan for now!

Check out the beginning of my backyard renovation if you haven’t seen it yet!

Tools Needed

  • 2 1/2″ decking screws
  • 1″ decking screws
  • Drill
  • Mitre Saw
  • Tin snips

Materials Needed

  • Tin
  • Decking board or 1×6 pressure treated wood

Cut List

  • 8 – decking boards or 1×6 pieces cut to 41 1/2″
  • 16 – decking boards or 1×6 cut ti 23 1/4″
  • 8 – 2×4 cut to 23 1/4″
  • 8 – decking board or 1×6 cut to 19 1/2″
  • 4 – tin pieces cut to 41 1/2″ length and 17″ width
  • 4 – tin pieces cut to 16″ width and 19″ length

Time needed: 3 hours.

Flower boxes can be pretty boring so I decided to go with steel on the sides to give them some character!

  1. Cut all the pieces first following the cut list

    If I have learned anything as a DIY’er it is to make all the necessary cuts all at once if you are following a guide. It makes everything so much easier.

    I used a Mitre Saw for the cuts and tin snips for the tin sections.

    PS. Cutting tin sucks…

  2. Make the support corners first as this will provide the structure

    I find that when I am building something that includes a frame that it is generally easier to build the frame first.

    With this project though building the corner pieces was the easiest and I will show you why as we go here.

    For the corners, you will need the 16 – 23 1/2″ (1×6) pieces and the 8 – 2×4 pieces. The 2×4’s add more support for your flower box.

    I had leftover 2×4 from my outdoor sectional so I used that!

    Lay one of the 1×6 boards on a level surface and screw a piece of 2×4 onto it using your 2 1/2″ screws.

    Take a second 1×6 board and attach to the 2×4 now creating a corner.

    Do this for all 4 corners for each box.

  3. Build the side pieces of the flower box next

    If you lay all the pieces out that you need as you go it makes building much smoother.

    For one side you will layout 2 – 41 1/2″ (1×6 boards) and a 1 – 41 1/2′ x 17″ piece of tin.

    Lay the 2 pieces of 1×6 board down on a level surface and set the piece of tin where you want it. Then using your 1″ decking screws, screw the tin into place.

    how to build a flower box using scrap wood

  4. Add tin

    tin inside diy flower box

  5. Attach the side pieces of the flower box to the corner supports now

    After you complete all 4 side pieces attach them to the corner pieces that you have already completed.

    Stand 2 corner pieces up at a time and attach one of your side pieces, one at each end. The side pieces will fit just inside the corner pieces to attach nicely!

    Continue until you have all the long sides and corners are attached.

  6. Complete the flower box by adding the end sections

    For the end section, you will need the 8 – 19 1/2″ 1×6 boards and the smaller pieces of tin that you precut for this build.

    Simply screw on your 19 1/2 pieces first, one on the top, and one on the bottom to create your side section.

    All that is left is to screw in your small sections of tin into your already attached 19 1/2″ pieces.

    side of flower box

  7. Add a base section

    After taking apart the massive flower beds that had routed I learned never to fill the beds completely full of soil…

    One, it is a ton of soil. Two, that much soil will quickly rot the wood.

    I decided to cut 2 pieces of some leftover 2×4 lengthwise and screw them about 8″ down on both boxes.

    Then I took some black flower mesh and staples it to the inside.

    This way, I only need about 7″ of soil for my annuals and the boxes can stay light for if I ever need to move them!


It was really fun creating this how to build a flower box post! As I look back through all the before and after pictures, I am amazed at just how much I have been able to create and build this summer.

This has been a strange summer for most as Covid has implemented so many restrictions.

I am thankful that I have a backyard to enjoy and the ability to use my hands to create a beautiful space.

You can also see most of my builds on Pinterest at tammybuilds.

Years ago I would have thought that I needed to hire someone else to make my space look anywhere near this nice. I am really proud that I have been able to do this!

For me, the best part of DIY is the satisfaction of stepping back and saying “I did that!”.

If you decide to make this flower box feel free to let me know what worked and what didn’t!

Tammy Seed

I am a passionate, goal oriented girl that loves DIY home projects and sharing with others how they can create and build easily as well!