How to Join Granny Squares: Multiple Techniques Explained

Making granny squares is satisfying. You finish one, then another, then suddenly you have a stack of colorful squares and the realization that you now need to turn them into a blanket. Joining is the step that transforms individual motifs into a finished project, and how you join them determines whether the blanket looks cohesive, whether the seams lie flat or create ridges, and whether the join becomes part of the design or disappears entirely.

There are at least half a dozen ways to join granny squares, and none of them is universally "best." The right method depends on the look you want, the yarn you're using, and how much time you're willing to spend. This guide covers the most common joining techniques, from nearly invisible sewing methods to decorative crochet joins that become a design feature. Each includes when to use it, how to do it, and what the finished result looks like.

Before You Join: Prepare Your Squares

Joining is much easier and the results are much cleaner when you prepare your squares first:

• Block all squares to the same size. Even squares made with the same pattern, yarn, and hook can vary slightly in size due to tension differences. Block them all to identical dimensions before joining. Squares that don't match will create puckered, uneven seams. The crochet blocking tutorial covers blocking methods for motifs.
• Weave in all ends before joining. Trying to weave in ends after squares are connected is fiddly and frustrating. Finish each square completely before assembly.
• Plan your layout. Arrange all squares on a flat surface (the floor, a bed, a large table) in the order you want them. Play with color placement. Move squares around until the arrangement pleases you. Take a photo. Stack squares in rows with labels (Row 1, Square 1; Row 1, Square 2; etc.) so you can reassemble them exactly.
• Decide on join orientation. Will you join squares with right sides facing each other (seam on the inside), wrong sides facing each other (seam visible on the right side as a decorative element), or right sides up (flat join)? Your choice affects which joining method makes sense.

Method 1: Whip Stitch Join (Fast and Strong)

The whip stitch is the quickest sewing method for joining squares. It creates a visible but neat seam and is excellent for beginners.

Best for: Blankets where speed matters, projects where a slight seam ridge is acceptable, joining squares of different colors where an invisible seam isn't possible.

How to do it:

1. Hold two squares with right sides together (or wrong sides together if you want the seam visible on the right side).
2. Thread a yarn needle with matching yarn (or contrasting, if you want the seam to be a design feature). The yarn should be the same weight as your squares.
3. Starting at one corner, insert the needle through both layers from back to front. Pull through, leaving a tail for weaving in.
4. Move slightly along the edge and insert the needle through both layers again, always in the same direction (back to front). Continue along the entire edge, placing stitches evenly — about one stitch per stitch or per row end on the square edge.
5. Pull each stitch to the same tension — snug but not tight enough to pucker.
6. At the opposite corner, weave in the tail to secure.

Result: A visible spiral of yarn along the seam line on the wrong side. On the right side, the seam is barely visible if the squares were held right sides together. A slight ridge may be felt at the seam.

Tip: For the classic granny square, whip stitch around the outermost round of each square creates a sturdy join that holds up well to frequent washing.

Method 2: Mattress Stitch Join (Nearly Invisible)

The mattress stitch creates the most invisible seam possible in crochet. When done well, the squares appear to flow into each other with no visible join line.

Best for: Projects where you want the squares to look seamless, joining squares in the same color, heirloom pieces where appearance matters most.

How to do it:

1. Lay two squares side by side with right sides facing up. The edges to be joined should be touching or nearly touching.
2. Thread a yarn needle with matching yarn.
3. Starting at the bottom corner, insert the needle under the horizontal bar between the first and second stitch on the edge of one square. Pull through.
4. Cross to the other square. Insert the needle under the corresponding horizontal bar on that square's edge.
5. Return to the first square. Move up one stitch and insert under the next horizontal bar.
6. Continue zigzagging between the squares, moving up one stitch at a time on each side.
7. Every 5-6 stitches, pull the yarn gently. The edges draw together and the seam disappears.

Result: The squares meet edge to edge with no visible seam from the right side. The join is nearly undetectable. The seam has good stretch and lies completely flat.

Tip: The mattress stitch works best when both squares have the same stitch count along the joining edge. Count your stitches before starting. If the counts differ slightly, ease the difference by skipping a stitch occasionally on the longer edge.

Method 3: Slip Stitch Join (Crochet Seam)

Using your crochet hook instead of a needle, the slip stitch join is faster than sewing and creates a visible but neat chain-like seam on one side.

Best for: Crocheters who prefer using a hook to a needle, projects where a flat seam is important, joining squares quickly.

How to do it:

1. Hold two squares with right sides together (or wrong sides together for visible seam).
2. Insert your hook through both layers — under the stitch tops of both squares.
3. Yarn over and pull through all loops (the fabric and the loop on your hook). One slip stitch complete.
4. Move to the next stitch position. Repeat across the edge.
5. Keep tension loose enough that the seam has stretch. Too-tight slip stitches create a stiff, puckered join.

Result: On the right side (if worked with right sides together), a subtle chain-like line is barely visible. On the wrong side, a raised ridge of slip stitches. The seam lies flat and has some stretch.

Method 4: Single Crochet Join (Decorative and Strong)

The single crochet join is intentionally visible and adds a structural ridge between squares. It's often worked in a contrasting color to create a grid effect across the finished blanket.

Best for: Blankets where you want the join to be part of the design, projects needing maximum seam strength, joining squares that will be heavily used and washed.

How to do it:

1. Hold two squares with wrong sides together (so the join will be prominent on the right side).
2. Attach yarn at one corner with a slip stitch.
3. Chain 1. Work a single crochet through both layers in the same corner.
4. Continue working single crochet through both layers along the entire edge.
5. At the far corner, fasten off or continue to the next square in the row.

Result: A raised ridge of single crochet stitches frames each square. In a contrasting color, it creates a striking grid pattern. The join is extremely strong and durable.

Tip: This is the ideal join for the best free crochet blanket patterns that feature granny squares in multiple colors. The contrast join ties the colors together visually.

Method 5: Flat Braid Join (Decorative Lacy Connection)

The flat braid join leaves a small gap between squares connected by a braided chain, creating a lacy, open look. It's more decorative than structural.

Best for: Lacy afghans, decorative throws, projects where the squares should look distinct rather than merged.

How to do it: The flat braid join uses chains and slip stitches to create a braided lattice between squares. The technique varies by pattern, but the basic concept is: work a round of chains and slip stitches around the edge of each square, then use those chains to connect adjacent squares, typically with a "chain 3, slip stitch to adjacent square, chain 3" sequence at connection points. Many patterns provide specific flat braid instructions.

Result: Squares are separated by a decorative braided border. The join is an intentional design element, not just a construction necessity.

Method 6: Join As You Go (JAYG) — No Sewing, No Seaming Afterward

Join As You Go is the most efficient method for blankets with many squares. You crochet the final round of each square and connect it to its neighbors simultaneously, eliminating the entire seaming step at the end. When you finish your last square, the blanket is already assembled.

Best for: Large blankets with many squares, crocheters who hate sewing, projects where you want to see progress immediately, gift projects with deadlines.

How to do it:

1. Complete your first square entirely, including the final round. This is your anchor square.
2. Work the second square to its final round. When you reach the edge that should connect to the first square, replace the chain spaces in that edge with slip stitches into the corresponding stitches of the completed square.
3. For a granny square: instead of "3 dc, ch 2, 3 dc" for the corner, work "3 dc, ch 1, sl st into corner ch-sp of completed square, ch 1, 3 dc." The slip stitch replaces one chain in the chain-2 space and connects the squares.
4. For the straight edges between corners: instead of chaining between shell groups, slip stitch into the corresponding space on the completed square.
5. Continue adding squares, connecting each new square to all adjacent completed squares at the edges where they touch.

Result: The squares are joined by small connecting stitches that blend into the final round. The join is subtle but visible. From the right side, it looks like a delicate ladder connecting the squares. From the wrong side, small connection points are visible. No sewing. No long seams. The blanket is finished when the last square's final round is complete.

Advantages: Eliminates all post-crochet assembly. Progress is visible and motivating — the blanket grows square by square. Ends can be woven in as each square is completed, so finishing work is distributed throughout the project rather than concentrated at the end.

Disadvantages: Requires planning — you need to know your layout before starting. Fixing a misplaced square means undoing the final round and rejoining. The technique takes practice to keep tension consistent at connection points.

Method 7: Flat Slip Stitch Join (Invisible from the Right Side)

This is a variation of the slip stitch join that's worked with right sides facing up, creating a completely flat, nearly invisible seam on the right side and a neat slip stitch line on the wrong side.

Best for: Projects where both sides will be visible (blankets without backing), crocheters who want an invisible join without sewing, joining squares with inconsistent edge stitch counts.

How to do it:

1. Lay two squares side by side with right sides facing up and edges touching.
2. Working from the right side, insert your hook through the back loop only of the edge stitch on the right square, then through the back loop only of the corresponding edge stitch on the left square.
3. Yarn over and pull through all loops — the two back loops and the loop on your hook.
4. Move to the next pair of edge stitches and repeat.
5. Keep tension loose and even. The join works because you're catching only the back loops, allowing the front loops to roll toward each other and hide the seam.

Result: The right side shows a subtle, nearly invisible join — the squares appear to float next to each other. The wrong side shows a neat line of slip stitches that lies flat against the fabric. The seam has excellent stretch and flexibility.

Why this method is different from the standard slip stitch join: The standard slip stitch join (Method 3) typically holds squares with right sides together, creating a raised ridge on the wrong side. This flat variation keeps right sides facing up, working through back loops only, which produces a completely different finish — flatter, more invisible, and attractive on both sides.

Method 8: Reverse Single Crochet Join (Crab Stitch Edge)

This decorative join uses reverse single crochet (crab stitch) to connect squares with a twisted, rope-like seam that's highly visible and intentionally decorative.

Best for: Projects where you want the join to be a bold design statement, joining solid-colored squares where contrast is desired, projects with a rustic or textured aesthetic.

How to do it:

1. Hold two squares with wrong sides together (so the seam will be prominent on the right side).
2. Working from left to right (for right-handed crocheters — opposite of normal crochet direction), insert your hook through both layers from front to back.
3. Yarn over and pull up a loop (two loops on hook).
4. Yarn over and pull through both loops. This is a reverse single crochet — it works exactly like a standard single crochet but in the opposite direction.
5. Move to the right to the next stitch position. Insert hook through both layers. Yarn over, pull up loop, yarn over, pull through both loops.
6. Continue across the edge. The stitches will naturally twist and create a textured, rope-like line.

Result: A prominent, twisted seam that sits on top of the fabric like decorative cording. In a contrasting color, it creates a bold outline around each square. The join is extremely strong and durable. It does not lie flat — it's a raised, textural element.

Disadvantages: Working in reverse is awkward at first and takes practice. The seam is bulky and not suitable for projects where a flat finish is desired. Uses more yarn than other joining methods.

How to Choose Your Joining Method

• Want invisible seams? Mattress stitch or flat slip stitch join.
• Want the fastest possible join? Whip stitch or standard slip stitch join.
• Want the join to be decorative but flat? Single crochet join in contrasting color, or flat braid join.
• Want the join to be decorative and textured? Reverse single crochet (crab stitch) join.
• Want to eliminate all seaming after the squares are made? Join As You Go.
• Want maximum durability for a heavily used blanket? Single crochet join, whip stitch, or reverse single crochet join.
• Want both sides to look good? Flat slip stitch join or Join As You Go.
• Joining squares that aren't all the same size? Whip stitch is the most forgiving for slight size variations.
• Joining dark-colored squares? Mattress stitch or flat slip stitch join — visible seams show less on dark yarn.

Joining Multiple Squares Efficiently

For blankets with many squares, joining them one pair at a time is tedious. Use these strategies:

• Join squares into rows first, then join rows together. Whip stitch or mattress stitch all squares into horizontal rows. Then join the rows to each other along the long edges.
• Continuous join methods: Some crochet joining methods allow you to join an entire blanket of squares without cutting the yarn, working continuously from one square to the next. The "join as you go" (JAYG) method is the most popular — you crochet the final round of each square and connect it to its neighbors simultaneously.
• Work on a flat surface. Joining squares in your lap leads to twisted, misaligned seams. Use a table or the floor. Keep the layout visible as you work so you don't accidentally join squares in the wrong order.