How to Join Yarn in Knitting
When you’re knitting away, you’ll eventually run out of yarn. At that point you need to start the next ball of yarn with a knitting technique called joining yarn. Join a new ball of yarn on an edge that will be enclosed in a seam whenever possible. If you can’t do that, then at least try not to start a new ball of yarn on an edge that will be exposed.
To join yarn at an edge, you can use either of these methods:
Knit the first stitch of the next row with both ends held together, drop the old strand, and carry on.
Knit the first few stitches with the new yarn only, stop, and tie the two ends together temporarily in a bow to secure them.
Either way, leave the ends at least 4 or 5 inches (10 to 13 centimeters) long so you can weave them in later with a yarn needle.
If you run out of yarn in the middle of a row, your options are the same: Tie a temporary knot with both yarns, leaving 4- or 5-inch (10- to 13-centimeter) ends; or knit the next stitch with both strands, drop the old one, and continue knitting from the new ball.