Or liners for your railing planters or fabulous vintage planter or …


So I’d like to know who came up with this concept of One Size Fits All?

Can you remember any OSFA thing, any OSFA at all, that when you tried it on, it actually fit? Fit like in a flattering way that is? Jewelry and scarves don’t count.

At a loss? Yea, me too!

So we’re in agreement on skirts, tops, jeans, etc. These are all meant for curves, our wonderful, challenging curves; and didn’t work out.

But surely a simple rectangle couldn’t be so difficult, right? Think again.

empty railing planter

Let’s skip right to it — to the humble window box or in my case, railing planters. How hard can it be to find a liner to fit the three vintage railing planters that were attached to the balcony when the house became ours? I’ll tell you: IMPOSSIBLE!

Odd length and short!

This calls for custom — and stylish, of course!

Let’s Make Custom-Sized DIY Window Box Liners:

The supply list is simple:



  • Burlap
  • Matching thread
  • Plastic craft mesh, optional






  • Sewing Machine
  • Measuring tape or ruler
  • Scissors
  • Straight Pins
  • Pencil

Step 1:

Measure your window Box

Length = Side to Side, the long side

Depth = Front to Back

Height = Top to Bottom

Mine measured 31″ in Length. But the depth varied. At the bottom, they are roughly 6-inches deep, but at the top of the frame they are 7-inches. They are only 4 1/2-inches tall.

I want mine to be 31 (L) x 7 (D) x 6 (H).

I’m adding 1 1/2-inches to the height. I add an inch last year (my first year of of these new planters). The extra height kinda flopped over, particularly on the long front side. A lot of people really liked that relaxed look. But I want to go with a more tailored, clean look this year. So I’m adding the optional plastic mesh inside to stiffen those long sides.

Step 2:

Cut Burlap

burlap fabric with ruler and tape measure

Let’s start by figuring your needed piece of burlap. First measurement:

Side to side calculation = length + height + height. [Mine this is 31 + 7 + 7 = 45]

Front to Back calculation = height + depth + height, now double all that and add 1-inch for a seam. [Mine is 6 + 7 + 6 = 19 X 2 = 38 + 1 = 39]

Now measure and cut a rectangle of burlap that is your side-by-side calculation by your front-to-back calculation. [Mine is 39″ x 45″]

Step 3:

Fold, Stitch and Press

burlap folded, stitched and pressed

Fold in half down the length of your Side-to-Side measurement [Mine is the 45-inch length, so my folded piece is now 45 x 19 1/2-inches].

Stitch down the long edge, forming a tube. Serge or zigzag is best, but a straight stitch will do.

Turn right side out and turn and press.

Step 4:

Mark and Stitch Corners

ruler on fabric showing placement of pin markers on long side

Lining up your raw edges, fold in half.

Mark from the center fold, half the length of your finished liner. [Mine is 31-inch length, so I marked at 15 1/2]. Top and bottom layers, and both sides, so four marks total.

ruler on burlap showing placement of pin markers on ends

Now mark the other ends. Again find the center. Then mark from the center half the depth of your liner. Both sides of center and both ends of the liner, four marks again. [Mine is depth of 7-inches, so I marked 3 1/2-inches out]

imaginary lines on burlap meeting to show where to mark for corners

Each side now has 4 marks (or pins). Each of the four corners now has 2 marks. Now create two imaginary lines to form a right angle at each corner based on your pins. Like the picture above.

Make sure they are true right angles. Use yardsticks and anything with a right angle you have handy — such as a book or album cover, remember those? Okay then a DVD case, remember those? Geesh, technology! Just grab a book — to help line things up.

Step 5 — Totally Optional:

Add Plastic Mesh to Sides

If, and only if, you are making a liner more than 1/2 inch taller than your planter, then you might want to consider adding some support for the front edge. And the long back edge if you are obsessive like me and your planter will hang from a railing rather than up against a house.

optional plastic mesh

I used these plastic mesh pieces that I had leftover from some old project.

Cut them the height of your liner. [Mine are cut 7-inches tall] Use as many as you need to support the front length, minus 2 inches. [I used 3 allowing them to overlap a bit]

Before closing us the ends, slip your supports inside and pin them in place along the long folded edge and the seamed edge, ending the supports an inch shy of the pins along that edge.

Run two rows of straight stitch along the row of support mesh. [I ran one row 1 1/2-inch and another row about 6-inches in from the edges]

Step 6:

Finish the Ends

Close up the raw ends with serging or zigzag stitching. Remove the pins and then replace them as you go or mark their spots with a pencil or faint marker.

This is where the magic happens and it all comes together!!!

Step 7:

Make Those Corners

fold corners on diagonal with pin markers meeting and intersecting mark on the fold line

At each corner, form a triangle or wing, by lining up the two pins or marks you have on the edges and the making sure the mark you made in Step 4 is on the fold.

Because my height and depth are close, my edges come close to lining up and my corner is close to a point. Yours may not be. Don’t worry about it. It’s most important for your Step 4 pencil mark to be on the fold and the two pin marks to line up on top of each other. One may be a bit shorter than the other, but that’s okay.

two stitched lines that for the corner wings

Now stitch two lines, each from the pair of pins or marks on the edge to the pencil mark on the fold line. These two pencil marks should line up with each other and they will form the folded base of your liner.

Now you have a pair of triangles or wings flapping around.

overlapping the corner wings to create the end

Pull them in together and overlap them as needed.

Because my liner is an inch taller than it is wide, my triangle points will be about an inch short of the side stitching.

pin the ends in place

Pin these in place and stitch this end using a straight stitch

overlapping wings stitched in place to form the end of the liner

And there you have it. If your liner is significantly shorter or taller than it is deep, your wings may wrap around the corner or barely meet on the sides. It’s all okay. Remember, this is NOT one size fits all!!!

empty liner in railing planter on balcony

empty liner in planter railing as seen from balcony

empty planter liner in railing planter seen from across

You can use your liner as I am with the crossing “wings” showing on the ends. I kind of like the envelope look.

Or your can flip your liner other-side-out. Because who’s to say which is the right side? And hide the wings inside under all the soil and greens.

And now your DIY Custom-Sized Window Box Liners are also custom style!

plastic lining the bottom of the empty liner

A layer of plastic in the bottom and up the sides just a bit will help your plants retain water — it’s a good thing for our plants, not so much for us!

And your DIY-ed custom size window box liner is ready for bright plantings and a summer of beauty!


  1. Michelle

    This is such a great idea! And they look so pretty, too.

    • Diane

      Thanks so much Michelle! Hope you give it a try and don’t hesitate to reach out with any questions.

  2. Kristin

    This is so helpful and inspiring! Thanks for sharing at Charming Homes & Gardens!

    • Diane

      Thanks so much for hosting Charming Homes & Gardens. I hope it inspires those with “difficult” planters.

  3. Julie Briones

    Okay, I LOVE this gardening craft! Perfect DIY window box liners. But i wanna know just one thing… How in the HECK did you get your photos from the front view of your balcony?!!!

    • Diane

      Ha! Ha! I brought in a boom truck.
      No really, our balcony is L-shaped with both the master bedroom and the living room opening onto it. There are five arches and three of them have planters on the railing. So I can stand on one corner and shoot with my zoom across the courtyard below.
      It’s a quirky 60’s “Bungilla” — It looks like a small bungalow from the front and a Mediterranean villa from the back.

  4. Sheri

    I just found this wonderful idea of yours. I have a question if this is still an active blog. Should the side to side measurement be length+height+height instead of length+depth+depth for the burlap window box liners?

    • Diane

      Hi Sheri, glad you found me! Yes, active, very active!
      Oh that’s a good catch!!! I’m editing that post right now. Thanks so much for bringing that to my attention.Yes, side to side measurement should be height + length + height.

      Thanks for being my editor!

      I’d love to see a pic when you get your done!



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