HOW TO join knitted squares

You’ve spent hours knitting beautiful squares, and now you have a pile of blocks ready to become a blanket. But how do you put them together without losing that professional finish?

In this guide, I’ll show you exactly how to join knitted squares using simple seaming techniques. Whether you prefer a completely invisible seam or a sturdy horizontal join, these step-by-step instructions will help you assemble your blanket with confidence. Let’s turn those individual blocks into a cozy masterpiece!”

The first step to assemble a blanket of knitted blocks is to decide the distribution of the pieces and block them. Some people prefer to block them first and then think about their distribution, and others choose to first decide the distribution and then block. I usually choose the second one because it allows me to block the squares in batches. This way, while the second batch of squares is drying up, I start sewing the first batch 🙂 If you don’t know how to block your squares or want to see a step-by-step guide to do it depending on the type of yarn you used, please take a look at my article on blocking.

Write a message in the comments section at the end if you have a question or need help at any point.

BLANKET ASSEMBLY EXAMPLE

To give you an example of the whole process I’ll share below the photos of the assembly of my “12 blocks for Xmas” blanket. If you want to knit more blocks to build more blankets, make sure to check my page “Free Beginner Dishcloths / Blanket Squares“. You will find lots of resources and inspiration there!

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Tools & Materials for Blanket Assembly

• Tapestry Needle: A blunt-tipped needle is essential so you don’t split the yarn fibers while seaming.
• Cotton Yarn: A matching color of fingering or sport-weight cotton yarn (even for wool blankets!) to ensure a sturdy, non-stretch join.
• Scissors: For trimming yarn tails.
• Measuring Tape (Optional): To check that your strips are aligning at the same length as you go.

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1) DISTRIBUTION OF THE BLOCKS

Play with them, placing them in different places until the layout is just as you want it to:

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2) JOINING BLOCKS

There are several ways to join the blocks, and I show below the ones that I use the most. Before choosing the method however, it is necessary to decide the direction of the joins that will be made first. I recommend that you always make the horizontal ones between blocks, for example, and then all the vertical joins. That’s what I usually do.

💡 Pro Tip: The Secret to a Sturdy Seam

Even if you are knitting your squares with wool or acrylic, I highly recommend using a matching color of cotton yarn(of the same weight) to sew your pieces together.

Why use cotton? Unlike wool, cotton yarn does not stretch. When you perform the “magic pull” to tighten your invisible seam, cotton provides a firm, stable hold that won’t give way over time. This ensures your seams stay tight and your blanket maintains its shape, even after many washes!

INVISIBLE HORIZONTAL SEAM

I use this seam to join one bound-off edge with one casted-on one (or two bound-off or two casted-on edges). You need to have the same amount of stitches in each piece because it is worked stitch by stitch, recreating a row. Here’s how to do it.

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💡 Pro Tip: Crochet hook selection

If you prefer to seam your squares by crocheting them together, use the same size hook as your knitting needles or go down a size. In the example below I used a 3.5mm hook for my 4mm knitted blocks to keep the seam from being too “loose”.

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VERTICAL SEAM

Once you finished joining your blocks with horizontal seams you’ll end up with strips of squares:

Now it’s time to join these strips. For an invisible seam you can use either mattress stitch (if you’re joining together pieces in stocking stitch), or edge-to-edge seam to join pieces with garter stitches at the sides. And, of course, you can also choose the single crochet seam I explained above to do it!

💡 Pro Tip: Seaming with Slipped-Stitch Edges

If you are joining blocks from my collections (like the Animals or Transports series, or the 12 Blocks for Xmas sampler blanket that illustrates this post), you likely followed my recommendation to slip the first stitch of every row. This creates a beautiful, sturdy edge with very defined “knots” instead of the looser loops produced when the first stitch is knitted.

To seam these vertically:

• Look for a “side knot” in the first edge, insert your tapestry needle from top to bottom (or from bottom to top, but keep it consistent over all your sewing!) and proceed to do the same on the second edge.
• Alternate side-to-side just like the mattress stitch. This will create a very flat, sturdy join that will go unnoticed!
• Note that, because we slipped the first stitch on every block (and every block has the same amount of rows), the ‘side knots’ will align perfectly 1-to-1, making it very easy to keep your seams even.

VERTICAL EDGE-TO-EDGE SEAM

Use this for a flat, nearly invisible join on garter stitch edges.

Step 1: Align Your Strips Lay your knitted strips side-by-side on a flat surface. Make sure the “right side” is facing up and the patterns or blocks are aligned exactly where you want them.

Step 2: Identify the “Side Knots” Look at the very edge of your work. Because you slipped the first stitch of every row, you will see a series of neat “knots” or horizontal bars. Since both blocks have the same row count, these knots will line up perfectly 1-to-1.

Step 3: Insert the Needle Thread your tapestry needle with your seaming yarn (remember the cotton yarn tip!). Insert the needle from bottom to top through the first “side knot” on the right-hand block.

Step 4: Cross to the Other Side Move to the left-hand block and insert the needle through the corresponding knot at the same level. Always keep your needle direction consistent (either always bottom-to-top or always top-to-bottom).

Step 5: Zig-Zag and Tighten Continue alternating side-to-side, catching one knot on the right and then one on the left. After every 2–3 inches, gently pull the seaming yarn. The two edges will pull together into a flat, sturdy join.

Here’s a close up of the seam:

Did you find this post useful? Let me know in the comments if you think there is some information missing, or if you have any more tips to share with Oh La Lana!’s community!

Hugs to you,

Cecilia