Join crochet squares
A seam joins matching edges; a slip-stitch join makes a ridge and a mattress-style join can sit flatter.
Work the technique
Block squares to the same measurements. Pair corners and stitch positions with markers. For a slip-stitch join hold right sides together and slip stitch through matching edge loops. For a flat sewn seam weave through opposing edge loops with right sides facing up.
Try it on a sample
Join two granny squares that each have four rounds. Match the four corner spaces and the intervening side clusters.
Check and recover
Do not force unequal edges together at one corner. Ease a small difference across the whole side; remake a substantially mismatched square.