Whip stitch, slip stitch, single crochet, mattress stitch, and join-as-you-go — with side-by-side notes on which looks best, holds up longest, and works fastest for large blankets.
You've stitched 42 granny squares. Now what? The join is where a blanket becomes finished — or where it stays a stack of squares for six months. Five common joining methods, honest pros and cons, and how to pick the right one for your project.
The classic. Thread a tapestry needle with matching yarn. Hold two squares with right sides facing (or wrong sides, if you want the seam to be a design element). Insert the needle through the outer loop of each square from back to front, working across the edge. Pull snug every three stitches.
Best for: quick joins, invisible seams (when worked through back loops only), any yarn weight. Downside: less structured than crocheted methods, so heavy blankets can stretch at the seams over time.
Hold squares with wrong sides together. Insert hook through the outer loop of both squares, yarn over, pull through everything. Continue across the edge. Creates a raised ridge on the right side of the fabric.
Best for: quick joins where you want a visible seam as a design line. Fast and structural. Downside: the ridge is visible from the front — either commit to it or pick a different method.
Same setup as slip stitch, but work single crochet through both squares instead. Creates a taller, more textured seam.
Best for: heavy-duty blankets that need structural seams. Downside: the seam becomes a design feature whether you want it to or not — plan the color accordingly.
The invisible sewn seam. Lay squares side by side with right sides up. Thread yarn on a tapestry needle. Alternately catch the outer bar of each square's edge stitch, zigzagging across. Pull snug every four stitches — the seam pulls the squares together and vanishes.
Best for: heirloom projects where seam invisibility matters most. Downside: slowest of the five methods.
You join squares to the growing blanket on the LAST round of each new square. Instead of chaining across the top corners, you slip-stitch into the corresponding corner of the previously joined square. No sewing at the end.
Best for: large blankets where the thought of joining 60 squares at the end is discouraging. Downside: requires more planning upfront — you commit to a layout before all squares are made.
Single crochet through both loops of both squares. It creates a firm, structured seam that holds up to heavy use and washing. The trade-off is a visible ridge on the right side.
Whip stitch with a tapestry needle. It's forgiving of uneven stitch counts, easy to un-do if you go wrong, and looks tidy when worked through the back loops only.
Yes, if you want the finished blanket to lie flat. Even factory-quality squares vary slightly in size; blocking makes them identical and drastically improves the final look.
For invisible seams, yes — matching yarn in the same weight. For decorative seams, a contrast color in the same weight looks intentional. Never join with thinner yarn; the seam will pucker.
A technique where you join each new square to the previously completed square on the last round of stitching, so no sewing is needed at the end. Great for large blankets, but requires deciding on your layout early.
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