Although it's not necessary to put a border on every afghan, most afghans look nicer with a border. The border adds an appealing finishing touch to the afghan. Many different types of afghan borders are available to use to finish the project, but a simple double crochet will match a double crocheted afghan nicely, even if the afghan was created using a different stitch. The double crochet adds an attractive thick border.
Start anywhere on the outside of the afghan after you have finished crocheting the afghan. Grasp the crochet hook in your right hand with the handle in your palm and your thumb and forefinger grasping the hook handle directly behind the hook. Hold the yarn in your left hand with the yarn woven over the first finger, under the second finger, over the third finger and under the pinky.
Place the yarn over the hook in a clockwise manner and push the hook into the first stitch, then place the yarn over the hook again and pull the hook out of the stitch. Place the yarn over the hook and pull the hook through two loops through the hook. Place the yarn over the hook one more time and pull through the remaining two hooks on the loop to finish one double crochet stitch.
Continue crocheting until you reach the last stitch in the row. Crochet two double crochet stitches in the last stitch.
Crochet two double crochets into the corner stitch. Crochet two more double crochets into the next stitch. This creates a flat corner on the afghan.
Continue across the border of the afghan crocheting six double crochets into the corner as you did previously. Cut the yarn 6 inches from the hook and tie a knot close to the afghan. Weave the end of the yarn in and out of the last few stitches.