Making a blanket with crochet squares allows you to use your imagination. You do not have to follow a set pattern and you can use any combination of stitches. You will end up with a truly one-of-a-kind crochet blanket.
Consider how you'll use the blanket. A crocheted blanket can be functional or decorative, and your preference will dictate the type of yarn and the pattern used. A functional blanket should be done in a solid stitch, while a decorative blanket, also known as an afghan, will use a Granny Square pattern.
Pick the yarn. If you want the crochet blanket to be functional, it should be warm without being too heavy. A two-ply yarn such as a sport weight or fingering yarn works fine. For the Granny Square, you would use the four-ply knitting worsted weight.
Measure for the functional crochet blanket. A 6-inch square is a good size. The blanket will cover the bed and the smaller squares will take the tension off of the stitches, making them less likely to stretch. Measure the width and the length and divide each one by 6 to know the number of squares you need. Leave room for a border of about 3 inches.
Measure for the Granny Square blanket. The Granny Square will be bigger and it will not cover the whole bed. The squares can actually measure from 6 inches to 12 inches, though 8-inch is a good size. It works up fast and even though you are using a heavier yarn, it still comes out light. Make one Granny Square and measure it. If it is too small, switch to a larger needle.
Make the squares. For a functional blanket, you can choose to do a single crochet, which will give you a tighter stitch, or a double crochet. Make a test square and see how it turns out. It takes a little time, but it is worth it in the end. You do not have to make every square the same. As long as it comes out the same size, you can do them in different stitches. An easy way to make sure they are square is to fold them diagonally. When the corners meet, they are perfectly square. For the Granny Square, you will have to follow a particular pattern; start out with a circle and turn it into a square by making clusters of stitches.
Join the squares. Lay out the squares first. With the functional blanket,you can create different looks by doing things like laying one with the rows going horizontal next to one with the rows going vertical. This gives the finished product a bit of a textured look. Whip stitch them together with a tapestry needle. This technique can be used for both styles.
Make a border using double crochet. Turn the corners by making three double crochet stitches in each corner. When you come back to the beginning, do not turn. Join the first stitch with a slip stitch and chain three and go around again. Three times around makes a nice size border.
Make sample squares with different size needles until it looks the way you want it to. This is a great way to use up yarn left over from other projects