While handmade cotton socks are cooler and more comfortable than wool socks during warmer months, 100 per cent cotton yarn is not the ideal fibre for sock knitting. Cotton does not have much fibre memory, and will not snap back to its original shape as well as other fibres will. In addition, it is not as durable as other materials. Most cotton sock yarns are a blend of cotton and nylon; on occasion wool or another animal fibre is blended with cotton.
Find a pattern. Using a pattern written specifically for cotton yarn will give you the best results. You may substitute cotton yarn in many sock knitting patterns; however, bear in mind cotton's lack of ability to hold its shape when you're choosing a pattern.
Begin your project. Caston for your socks using a stretchy technique, such as Judy's Magic Cast-On for toe up socks, or the Old Norwegian cast-on for top-down patterns. Cotton isn't as stretchy as other fibres, so make sure your cast-on is loose enough to accommodate your foot.
Knit the sock's cuff. There are a variety of knitting techniques to help cotton behave in a more elastic manner. According to the site socknitters.com, knitting the ribbing on the cuff with smaller needles, or twisting the ribbing by knitting into the back stitch will help the socks stay up on the leg.
Cast-off and finish the sock. Use a stretchy cast-off technique such as Jeny's Surprisingly Stretchy Cast-Off to ensure that the sock will fit comfortably. If your cotton socks tend to slouch, consider weaving elastic thread through the top of the cuff to provide an extra bit of stretch.
Tip
Cotton yarn is absorbent and will pull moisture from your fingers. Make sure you moisturise frequently while you are knitting with it. Because cotton yarn isn't as stretchy as other fibres, it can cause hand fatigue. Take frequent breaks to stretch out your fingers while you are knitting with it to avoid strain and injury.