Assemble granny square afghan

[Bk2973]

Hi, I need a help on how to sew granny squares together. One of those I crocheted was a baby afghan and I used invisible stitch all horizontally and then vertically, both continuously from one end to other end. However, the squares didn’t stay and secure. When I shake, the squares slid to one end and afghan became scrunched up. What did I do wrong?

[Granny Square]

What are you calling invisible stitch?  The method that comes to mind by that description is the mattress stitch, but I'm having trouble imagining "shaking" the blanket and the squares moving around, because you should be joining in multiple directions. 

The best method IMO is too late for you now, (Unless you want to pick the seam apart and start over with squares) called 'join as you go'.  Finish square 1.  On the last round of square 2, connect to square 1 on one side.  On the last round  of square 3, connect to one of the other squares on 1 side. And so on; if you google 'join as you go' you will find a ton of ways to do this, some simple, some fancy.  The easiest is. for a traditional granny square, to join squares between the groups of 3 DC (I call them shells) on the last row, as in : on the square you are finishing, instead of chaining 1 or 2 after a shell, reach over to the square you want to join to at the corresponding spot and (one way) is to ch1, slip stitch into that spot, ch1, continue on the shell you were working on, repeat.  There is no way that anything can 'move around' this way.

Another easy way is a contiguous join, here is one example.

 

[bgs]

Sounds like running stitch was used and its used to gather fabric.  Still hard to imagine it moving that much if all 4 sides of each square were stitched to its adjacent square.

Edited March 28, 2022 by bgs

[NCcountrygal]

Maybe, this will help. 10 Ways to Join Granny Squares • RaffamusaDesigns

(posted in the crochet reference section of Crochetville)