What sashing is and why you use it

Sashing is the fabric strip you sew between quilt blocks to frame them and add space to your design. It sits like a border around each block, separating one from the next, and makes blocks appear larger without adding more piecing work. Sashing also lets you adjust the final quilt size by changing the width of the strips or adding corner squares where they meet.

Sashing serves two practical purposes: it gives your eye a place to rest between busy block patterns, and it solves the math problem of getting blocks to fit together. If your blocks are 10 inches square but your design calls for 12-inch spacing, sashing fills that gap cleanly. Most quilters use sashing 1.5 to 2.5 inches wide, though you can go wider or narrower depending on your design.

Key Takeaways

  • Cut sashing strips the length of your block plus seam allowances, and cut them all the same width so your finished quilt stays square.
  • Sew sashing to opposite sides of each block first, then add sashing to the remaining two sides, pressing after each seam to keep blocks flat.
  • Corner squares (small pieces where sashing strips meet) are optional but make assembly faster and let you add color contrast to your design.
  • Chain piecing sashing onto multiple blocks at once saves thread and keeps your sewing rhythm steady.
  • Press sashing seams toward the sashing strip, not toward the block, so the seam allowance lies flat under the strip.

Measuring and cutting sashing strips

Measure your finished block size first. If your block finishes at 10 inches, add 0.5 inches for seam allowances on each side — so your block is actually 10.5 inches cut. Now decide how wide you want your sashing to finish. A 1.5-inch finished width is standard; add 0.5 inches for seam allowances, making your cut width 2 inches.

Cut your sashing strips to the length of your block plus seam allowances. For a 10.5-inch block with 2-inch-wide sashing, cut vertical sashing strips 10.5 inches long and 2 inches wide. Cut horizontal sashing strips the width of your block plus two sashing strips plus seam allowances — for example, if you're sashing two blocks side by side, that's 10.5 + 2 + 10.5 + 2 = 25 inches long. Use a rotary cutter and ruler to keep all strips the same width; uneven sashing will throw off your block alignment.

Cut all your sashing strips before you start sewing. Lay them out next to your blocks so you can see the color balance and make sure you have enough. If you're using corner squares, cut those now too — they're usually the same width as your finished sashing (1.5 inches finished, 2 inches cut).

Sewing sashing to the sides of blocks

Start by sewing sashing to two opposite sides of each block. Place a sashing strip right sides together with one edge of your block, aligning the raw edges. Sew with a quarter-inch seam allowance — the standard for quilting. Use a walking foot if your machine has one; it feeds fabric evenly and prevents the block from shifting.

Press the seam toward the sashing strip, not toward the block. This keeps the seam allowance from creating a bump under the block fabric. Trim any threads and flip the block over to check that the seam is straight and the block hasn't puckered. Repeat on the opposite side of the block.

Now sew sashing to the remaining two sides. These strips will be longer because they cover the block plus the sashing you just added. Align, sew, and press the same way. Your block is now framed on all four sides.

Using corner squares to connect sashing strips

Corner squares are small fabric pieces that sit where horizontal and vertical sashing strips meet. They're optional, but they speed up assembly and let you add a contrasting color or pattern to your design. Cut them to match your sashing width — if your sashing finishes at 1.5 inches, cut corner squares 2 inches (including seam allowances).

When you're ready to join blocks into rows, sew a corner square to the end of each horizontal sashing strip. Then sew that strip to the top or bottom of a block. The corner square sits at the intersection, creating a grid pattern. This method is faster than measuring and cutting custom-length sashing strips for every row.

If you skip corner squares, you'll cut longer sashing strips that span multiple blocks and sew them all at once. Both methods work; corner squares just give you more control over color placement and are easier to cut in batches.

Chain piecing sashing for speed

Chain piecing means sewing multiple pieces in a row without cutting the thread between them. Line up your first block and sashing strip, sew them together, then feed in the next pair without stopping. After you've sewn all your pairs, snip the threads between them and press.

This method saves thread, keeps your sewing machine in rhythm, and makes the work feel less repetitive. It works especially well when you're sashing many blocks at once. Lay out all your blocks and sashing strips in order before you start, so you can feed them smoothly without hunting for the next piece.

After chain piecing, press all the seams in the same direction before you move to the next step. This prevents seams from bunching when you join rows together later.

Pressing and squaring up blocks after sashing

Press each block after you add sashing to all four sides. Use a hot, dry iron and press from the back first, then flip and press the front. This sets the seams and flattens any wrinkles. If a seam is puckered, spray it lightly with water and press again.

Once all blocks are pressed, square them up using a large square ruler. Place the ruler over the block and trim any edges that stick out past the ruler's edge. This ensures all your blocks are exactly the same size before you join them into rows. Uneven blocks will create gaps and make your quilt top wavy.

Measure from the center of the block outward to make sure you're trimming evenly on all sides. If you trim too much from one side, your block will be off-center. A quarter-inch trim on each side is usually enough; if you need to trim more, check that your seam allowances were accurate.

Joining sashed blocks into rows and the quilt top

Once all blocks are sashed and squared, join them into rows. Sew blocks together side by side, pressing seams to one side after each row. Then sew rows together, pressing seams in alternating directions so they nest together and lie flat.

If you used corner squares, the grid pattern will guide you — each corner square should align with the corner squares in the rows above and below. If you cut long sashing strips instead, make sure the seams line up by pinning before you sew. Offset seams create visible steps in your quilt top.

After the quilt top is assembled, press it one more time from the back, then the front. Check that all corners are square and the edges are straight. If the quilt top is wavy or the corners are off, you may need to trim the edges slightly or adjust how you press the seams.

Frequently Asked Questions

What width should my sashing be?

Most quilters use sashing that finishes between 1.5 and 2.5 inches wide. Narrower sashing (1 inch) makes blocks feel connected; wider sashing (3 inches or more) creates a bold frame. Choose based on your block size and design — larger blocks usually look better with wider sashing.

Do I have to use corner squares?

No. Corner squares are a convenience, not a requirement. Without them, you cut longer sashing strips that span multiple blocks and sew them all at once. Both methods produce the same result; corner squares just give you more flexibility with color and are easier to cut in batches.

Which direction should I press sashing seams?

Press toward the sashing strip, away from the block. This keeps the seam allowance from creating a visible ridge under the block fabric. When you join rows, press seams in alternating directions so they nest together and the quilt top lies flat.

How do I keep my blocks square after adding sashing?

Use a large square ruler to trim the edges after pressing. Place the ruler over the block and trim any fabric that extends past the ruler's edge. Measure from the center outward to trim evenly on all sides, and check that your seam allowances were a consistent quarter inch.

Can I use different sashing widths in the same quilt?

You can, but it makes the math harder and the quilt top may not lie flat. Stick to one sashing width throughout unless you're intentionally creating a modern or asymmetrical design. If you do vary widths, plan it on paper first and measure carefully as you sew.