The Secret to Invisible Joins: Mattress versus Ladder Stitch for Granny Squares

There’s something so satisfying about seeing a stack of colorful granny squares ready to become a blanket, pillow, or cozy cardigan. But that moment of joy can also come with a familiar question: what’s the best way to join them? Enter the Mattress (also called Ladder) stitch — the secret weapon for crocheters who crave a clean, invisible seam that looks as polished as it feels. This joining technique transforms individual squares into a single, smooth fabric with minimal bulk and a beautifully seamless look. Whether you’re building a color-block afghan or a patchwork sweater, the mattress stitch is what makes your project look finished, professional, and effortlessly sleek.

If you’ve ever struggled with lumpy joins or misaligned edges, this guide is for you. Here, you’ll find step-by-step photos and detailed explanations that walk you through the entire process — from laying out your squares for efficient joining, to keeping them perfectly aligned, to mastering the start and finish without any loose ends. I’ll also show you which types of granny squares pair best with the mattress stitch, when to use slight variations in technique, and how to secure your yarn invisibly for a lasting join that can stand up to years of snuggling.

Joining granny squares doesn’t have to feel intimidating — it can be just as meditative and creative as crocheting the squares themselves. Once you get the rhythm of weaving the stitches together, watching your blanket come to life row by row becomes seriously addictive! The mattress stitch is not just a method; it’s a moment in your project where everything starts to come together — literally and creatively.

When is the Mattress Stitch the best option?

The mattress stitch really shines when you’re joining classic-style granny squares that have two chain spaces in each corner. Those open corners make it easy to align your squares and weave the seam neatly between the stitches on either side. Because the seam sits flat and pulls the edges together invisibly, it’s ideal for projects where you want the granny square design itself to be the focal point — all those decorative stitches, color changes, and textures stay front and center without a bulky ridge to distract the eye.

This technique also works beautifully for detailed or highly decorative squares, such as floral motifs or complex lace-style designs, since the stitch practically disappears once it’s tightened. For the cleanest finish, use a joining yarn that matches the outermost round of your squares. If your project includes many different colors, pick the shade that’s least likely to contrast — usually a neutral or one that blends softly with most of your outer edges. That way, your join stays hidden, and the beautiful details of your handiwork take the spotlight.

Mattress versus Ladder - what's the difference?

Although the mattress stitch and ladder stitch are often used interchangeably in crochet and sewing communities, there’s a subtle difference between them that’s worth noting before you get started. Both methods create an invisible seam, letting you join pieces cleanly without bulky ridges or visible stitches. However, one technique delivers a slightly tighter and more concealed result than the other — perfect for those projects where every detail matters.

With the ladder stitch (top example), your needle moves from front to back through the back loop of each outer stitch, alternating from one square to the other. As you continue, your thread forms little “rungs” that resemble a ladder, which is how the stitch got its name. The mattress stitch (bottom example), on the other hand, adds an extra step: after inserting the needle into the back loop of a stitch, you return it to the front through the back loop of the next stitch on the same square before crossing to the opposite side. This small difference pulls the edges closer together, creating a stronger, firmer seam with virtually invisible joins. The result is a smoother, cleaner connection that blends seamlessly into your granny squares.

As with any granny square project, it is crucial to align your sides correctly. Here's a tip that could help you keep your sides aligned and prevent some mistakes down the road: use stitch markers! Identify your 2-chain corners and place the markers into the corresponding corner loops. Ensure that the number of stitches you have between these markers are the same on each side. If they're not, double check your marker placement before you make any joining stitches.

Now let's see our joining stitches in practice!

Ladder Stitch

Begin by cutting a long length of yarn and threading a darning or embroidery needle. Take 2 squares that you will join and place them on a flat surface with the front sides facing up.

Insert your needle from the front of your first square (orange in my example) into the back loop of the corner chain that is closest to the side you will join - the blue marker in my example. Pull the yarn through leaving at least a 6-inch yarn tail that you can work with later to secure your joining yarn. Next, insert your needle from the front of the second square (green in my example) into the back loop of the corresponding corner chain on the 2nd square - this is the yellow marker in my example. Pull the yarn through until you have about an inch of space between your two squares (last image below).

Now in the first square, insert your needle from the front into the back loop of the next stitch (this loop should be empty). Then in the second square, insert your needle from the front into the back loop of the next corresponding stitch (center image below). Repeat this process, alternating between the first and second squares, inserting your needle from the front of the square into the back loops of each stitch. Do not reinsert your needle into a stitch that already has joining yarn in it.

When you get to the end of your sides, pull the joining yarn tight to close the seam.

As you can see from this image, the ladder stitch does not completely close the gap between your squares. You can still see a bit of the yellow joining yarn between the squares in my example.

Mattress Stitch

Begin by cutting a long length of yarn and threading a darning or embroidery needle. Take 2 squares that you will join and place them on a flat surface with the front sides facing up.

Identify the lower 2-chain corner of the 1st square (in my example the orange square), of the side you will join. Insert your needle from the front of the square into the lower chain, in the back loop only (first image below). Next, insert your needle from the back into the next corner chain - the one closest to the side that you will join. Repeat this to make another loop. This will secure, or anchor, your yarn to this square's corner.

Now repeat the first step with the 2nd square (the green square in my example), inserting your needle from the front into the lower corner chain, then from the back into the 2nd corner chain (first image below). Next, insert your needle from the front into the back loop of the corner chain closest to the side you will join (you're inserting the needle back into this space, this time from the front). Then, insert your needle from the back into the back loop of the very next stitch (last image below).

Repeat this step for the 2nd square, inserting your needle from the front into the back loop of the closest corner chain to the side you will join (first image below). Then, insert it from the back into the back loop of the next stitch (center image below). Go back to the 1st square and repeat this process - insert from the front into the back loop of the same stitch you did from the back, then insert from the back into the back loop of the next stitch (last image below).

Repeat this process all the way down the side of the squares to join them - inserting your needle from the front of the back loop of the stitch you previously came out of from the back, then insert into the back loop of the next stitch on the same square, from the back.

After making a few stitches, pull the yarn to bring the two sides together (center image below). Make a few more stitches, then pull together.

As you can see from the images, the mattress stitch creates a truly invisible seam between the squares - even a contrasting color is hidden behind the fabric.

So which one should you choose?

When it comes down to choosing between the ladder stitch and the mattress stitch, the differences are subtle but worth considering. In terms of time and yarn, the trade-off between the two is marginal, so if your goal is a truly invisible join, the mattress stitch comes out ahead. It pulls the squares more closely together, pressing the edges into a neat, firm seam that all but disappears into your work. For that reason, it is usually the better option when you really want the design of your granny squares to shine without any visible interruption.

So why might someone still choose the ladder stitch? A crafter might prefer it if they want a slightly quicker joining method and do not mind a looser, more relaxed seam. On projects where all the outer rounds of the squares are the same color, the visibility difference between ladder and mattress becomes almost negligible, especially if the same yarn is used for joining. In those cases, either method will blend in nicely, and the choice really comes down to personal preference and the feel you want in the finished fabric. The choice is always up to the maker—but for most of my projects, the mattress stitch is the seam of choice.

Joining multiple squares

Chances are, you have more than 2 squares to join, so I will walk you through the steps you'll need to take to continue joining the next several squares.

Regardless of the stitch method you chose, the next steps will be the same. However, I will show the mattress stitch in the reference photos so you can follow along.

After you've finished stitching into the 2-chain corner on your second square (green in my example), move on to the next two squares. Your third square (green in my example) is where you will begin joining. Insert your hook from the front into the back loop of the first chain in the corner, then insert from the back into the back loop of the second chain in the corner (the one that is closest to the side you will join). Pull these stitches tight and continue up the sides to join these two squares - exactly as you did to join the first.

Continue joining more squares this way until you get to the end of your run. This section, consisting of 2 columns of squares, should have the number of rows that you want in your final fabric. If you run out of joining yarn in this process, leave yourself plenty of yarn to work with as you will need at least 6 inches to work in later. Don't short yourself on this - it's better to have too much of a yarn tail leftover than not enough.

In the perpendicular direction, anchor your joining yarn just like you did at the start of your column, wrapping around one corner. Perform your mattress or ladder stitch up to your first 4-way corner (first image below). After you've stitched into your last available loops, pull your stitches securely, then insert your needle into the front loops of the corner chains directly above the last stitch that you made (center image below). This is the only time that you will insert your needle into the front loops. This helps to pinch those corner seams together securely so no joining yarn will be visible when you're finished. Insert your needle from the back of the first chain and then from the front into the second chain (front loops). Repeat this for the corner chains of the third square (last image below).

Repeat this process to go around the 4-way corner completely, inserting your needle into the front loops of each square. When you get back to the 2nd square (the square you made your last ladder or mattress stitch), make one more pass into the front loops of the corner chains in the square directly above it (green in my example, last image below).

In the last image below, you'll notice that I've made a complete revolution with the joining yarn, stitching into the front loops of all four squares, but going back in a second time into that top green square. Doing this puts us in the correct position for the next ladder or mattress stitches as we continue along our next square sides.

Pull your corner stitches tight (first image below). Continue your ladder or mattress stitch along the sides of your third and fourth squares. The back loops of your first stitches can slouch easily behind the stitches you made into the front loops of your corners. Be sure you are inserting into the back loop of your first corner stitch from the front, and then into the back loop of the next stitch from the back (center image below). Continue with your ladder or mattress stitch to finish joining your third and fourth squares (last image below).

Once you reach the end of your seam between your third and fourth squares, repeat the same corner join process to attach your fifth and sixth squares. Be sure to check the tension of your seam before moving to the corner join - once that corner join is secure, you will not be able to adjust the tension of the previous seam. The tension should be consistent across all sides of your squares.

Weaving in those yarn tails

Now this is a question I get asked a lot: how do I finish off the seams and secure the yarn tails? There is no one option that works for every situation. I will give you a few techniques that I use, and you can choose what's best for your project.

One thing that I will caution you about is this - do not tie knots! Knot tying anywhere in your fabric can create an unnatural buckling. Your finished granny square fabric - whether its a blanket or a garment - should flex and stretch evenly. If you're concerned about unraveling, sew your yarn tail once or twice around the last stitch that you made (just like you did for the anchor at the beginning of the mattress stitch), and then leave yourself a tail of at least 6 inches to weave in.

Option 1: hide your yarn tails into your border. Many granny square projects, especially blankets, are completed with a complimentary border around the entire perimeter of the piece. Any yarn tails lingering along the outer edge of your square assembly can be hidden into this border. This technique works best for solid borders where no outer stitches are skipped, and for borders where the yarn color matches the yarn used for the seams.

Begin crocheting your border (any stitch will do). When you come to the point where your yarn tail starts, lay it down over the tops of your next stitches. Crochet into your outer stitches as normal, ensuring that the yarn tail is locked inside each stitch (center image below). Complete your border. If you have an exceptionally long tail to hide into your work, cut it down to about 6 inches or so. Don't hide two or more yarn tails in the same border stitches - this can actually add to the height of your stitches, making your border uneven. Try to leave only one yarn tail to hide into your border per square.

Option 2: weave your yarn tails into your stitches. This works best when the joining yarn is the same color as the outer rows of the squares.

Thread your yarn tail into your needle. On the back of your square, insert your hook through the loops of your stitches (center image below). Be careful not to split the strands of the yarn while you sew through the loops - the stitches should be able to stretch and flex normally. Sew into as many stitches as you'd like, but do not cross the yarn over into a new square. Try to keep each yarn tail to a single square. Trim off any excess that you won't weave in.

Option 3: weave your yarn tails into the back of your seams. This works best when the joining yarn is a different color than the last row of the granny squares. It's a last resort for my projects, only when color-matching isn't possible. I also reserve this technique for projects where the back side of my work is not visible, such as a garment or a tote bag that can be lined.

Thread your yarn tail into your needle. On the back of your square, insert your hook into back loops across both sides (first image below). Alternate direction and repeat this along the back of your seam. Do not sew across multiple columns of squares. Sew this yarn tail along one seam only. Trim any excess.

In conclusion...

The mattress and ladder stitch are both fast, flexible, and beautifully clean ways to join your crochet pieces, especially when you’re working with multiple granny squares in long columns and rows. Once you understand the rhythm of the stitch and learn how to manage tension, keep your squares aligned, and secure your starting tails and ending yarn ends, you’ll find yourself using these techniques again and again for all kinds of projects. From planning your layout, to joining each square neatly, to weaving in those final ends, these methods are perfect for anyone who loves tidy seams and professional-looking results—no bulky ridges or distracting joins required.

If this tutorial helped you, I’d love to hear from you! Drop a comment below, give the post a like, or reach out with your questions—I enjoy connecting with fellow crocheters and hearing how you use these techniques in your own creations. Happy stitching, and may your joins always be smooth and seamless!