This blanket is made with Stylecraft Special DK yarn in Parchment, Teal, Sage, Petrol & Duck Egg with Graphite for the joining and border.
The squares are solid grannies (6 rounds each)
I joined them using the Flat Braid Join. The Patchwork Heart has a great tutorial here. In her tutorial is the option to do a round of DC (UK terms) on each square in the joining colour to make the join appear wider. I did this.
Finally I used Edge #93 from Around the Corner Crochet Borders by Edie Eckman