Stitch an Ohio Star Quilt Block: How to Read an exploded Quilt Block Diagram

The first quilt block I decided to tackle in my 12 Classic Quilt Blocks sampler is the Ohio Star—a very popular block that dates to the 19th century. The Ohio Star is a nine-patch quilt block that features quarter-square triangles and corner posts around a central square.

Like all the blocks on our 12 Classic Quilt Blocks download, this version of the Ohio Star shows an exploded diagram and a cutting list, but no step-by-step instructions. It is the essence of what you need to know to stitch ONE block with no frills. When you’re sewing from an exploded diagram, take a moment to look it over carefully!


Using the diagram above as an example, let’s talk about how to read an exploded quilt block diagram.

  • At the top left, you’ll see an illustration of how the finished block will look.
  • In the center, you’ll see a line drawing of the pieces that make up the quilt block. The letters correspond to the cutting instructions at the bottom—this block has two pieces: a square, A, and a triangle, B. (You can use this line drawing to note your fabrics or colors.)
  • At the top left, you see the block “exploded”. This illustration shows you how the fabric pieces are put together to construct the block. (Generally speaking, all the units in an exploded diagram are the basic building blocks of patchwork, like half-square or quarter-square triangles, and you can use your favorite method to stitch these.) This particular illustration is showing us that we’ll stitch the units into rows, then sew the rows together.
  • At the bottom, you’ll see the cutting instructions. This grid gives you four different finished sizes to choose from. Each column tells you the size to cut the given shape.

For my Ohio Star, I’m using white, pink and purple fabrics for my block. I can read down the 6” column and see that I’ll need five 2-1/2” squares and one 3-1/4” square, cut into four quarter-square triangles from the white fabric; two 3-1/4” squares, cut into eight quarter-square triangles from the pink fabric, and one 3-1/4” square, cut into four quarter-square triangles from the purple fabric. (If you’re stitching up more than one block, be sure to make a note of how many of each piece to cut!)

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I like to lay my pieces out just like the exploded diagram to ensure I have the right number of pieces, and I like the way the fabrics look together. Once the pieces are cut, it is time to sew!

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Chain piecing definitely speeds things up. You can see my leaders and enders in this picture—these pieces are very helpful in making sure the small points or pieces don’t get pulled down into the feed dogs.

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Match your seams carefully when stitching the quarter-square triangles together.

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After getting each patch sewn up, it is time to stitch the units into rows.

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Once the rows are sewn together, sew the rows together. Taking special care to match your seams will give you perfect points on your finished block.

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Voila! An Ohio Star ready to stich into a quilt top!

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