An afterthought heel is exactly what it sounds like – one that is done after the rest of the sock is completed. The entire sock is created from top to cuff (or vice versa) and a placeholder is put in for the heel. Then, after the rest of the sock is completed, the heel is inserted. Normally, in this case, the heel messes up the stripes on the front of the sock (see image). But with an afterthought heel, the striping is maintained perfectly and even the heel is striped.

This is an example of a sock done with self-striping yarn but without an afterthought heel. Notice how the dark purple stripes are not regular – the purple is really thin right opposite of the heel.

Here is a sock with an afterthought heel and self-striping yarn. Notice how the stripes in the front are even and uninterrupted?

How to Create an Afterthought Heel

1. Knit your sock, either from the top-up or the cuff down.
2. 

   Shows a sock with waste yarn in purple (right below the ribbing)

   When you get to the part of the sock where you would normally put in the heel, knit the 1/2 of the sock with waste yarn. If you are using Magic Loop, you would knit one needle with waste yarn. If you are knitting with 5 DPNs, knit 2 needles with waste yarn. Simply drop your working yarn and start knitting with waste yarn, leaving a tail. Then, when you get to halfway around the sock, pick the working yarn back up again, leaving a bit of slack and cut the waste yarn.

3. Knit a few more rows with stockinette stitch at the back, then change to your cuff pattern all the way around. Finish your cuff and cast off.
4. 

   Use your needles to pick up the stitches along the waste yarn.

   Pick up the stitches on both sides of your waste yarn. With Magic Loop, one side of the waste yarn is on one needle and the other on the other needle. You are going to knit these stitches in the round. The stitches (if they are stockinette) will form a “v”. Pick up the ONE of the 2 legs of the stitch. Generally if you have the work facing the same way it will be when you knit it, you want to pick up the right leg.

5. Using a yarn needle, pick out the waste yarn, leaving the stitches on the needle. You can start from either end.
   

   Using a needle, pick out the waste yarn.

   Here’s what it looks like when the waste yarn is being removed.

6. Start knitting the heel in the round. Knit 2 rows.
7. Start decreasing. Using the decrease method of your choice, decrease 4 times on every other row just as you would a toe in cuff-down socks. Be especially carefulto keep your stitches tight between needles. This part is especially prone to laddering! On magic loop, I did as follows:
   1. Row 1: On each needle, k2tog, knit to last 2 stitches on needle, ssk.
   2. Row 2: knit all.
8. When about 1/2 the stitches remain on the needles, start decreases 4 times on every row. Do this for 4 rows.
9. Cast off using the Kitchener stitch (grafting).

And that’s it. You should finish with a heel that looks great, is comfortable, and has nice stripes in it to match the rest of your sock.

Let me know in the comments if you plan to give this a try!