After you finished knitting the main part of your sock it’s time to make the hem.
Begin by knitting 7 plain rounds, then *yo, k2tog* around, then 6 more plain rounds.
You can make the hem as deep as you like, but you always want the section above the yo round to be one less then the section below.
Once you have knit the picot hem. Place all the stitches on a piece of waste yarn, this will make it easier to sew and to see what you are doing.
Turn your sock inside out. fold down the hem so that you are pleased with the way your picots look, make a note of where the edge lands, this is the purl row you will be sewing into.
Using your yarn tail, which you cut to 2 – 3 times the circumference of your sock, sew purl-wise through the first live stitch.
Then sew through the purl bump on the previously noted row that falls below your first stitch.
You will be sewing from the top downwards.
Pull the yarn snug, but not too tight
Continue in this manner: purl wise through the next stitch, then top to bottom through the next purl bump.
After a few stitches, I find it faster to sew through both the stitch and the bump at the same time.
After you have finished sewing the entire hem. Sew once more through the first stitch and it's corresponding purl bump to finish off.
To make sure that your hem will be stretchy enough to get on, give it a good stretch before weaving in the ends.
Remove the waste yarn, by simply pulling on one end, it should slide freely out of your hem.
and admire your spiffy sewing job.
and there you go. this method can also be used to make decorative hems on top down sweaters and sleeves. If you have any questions or comments feel free to ask.