There is one trick to changing color in crochet, and once you know it, stripes stop looking amateur.

You make the change on the final yarn-over of the last stitch in the old color — not at the start of the new row.

That single detail is the difference between a crisp color line and a stripe with a stray dot of the wrong color at the edge of every row.

The basic color change

Work your last stitch in the old color, but stop one step short of finishing it — leave the final two loops on the hook.

Work the stitch normally until two loops remain on the hook.
Drop the old color. Yarn over with the new color.
Pull the new color through those two loops to complete the stitch.

The stitch is now finished, and the loop on your hook is the new color, ready to continue. The completed stitch keeps the old color on its body, with the new color only in its top.

Leave both tails hanging about six inches for weaving in later, and carry on.

Changing color between rows

Here is where people go wrong. If you finish the row in the old color, then turn and chain up in the new color, that turning chain is fine — but the last stitch of the previous row is now the old color, sitting right at the edge where the new stripe begins. It reads as a mistake.

So make the change during the last stitch of the previous row. Complete the final stitch of the old-color row using the new color, as above. Then turn, and your turning chain is already the new color, and the color line runs perfectly straight up the edge.

Test it once. Work four rows of single crochet: change color the wrong way (at the start of the row) for the first change, and the right way (in the last stitch of the previous row) for the second. Put the swatch next to a window. The difference is immediately obvious, and you will never do it the wrong way again.

Changing color mid-round

In the round it is the same mechanism, with one extra consideration: joined rounds give you a natural place for the change, right at the join, and the seam hides it.

In a spiral there is no join, so a color change is always a slightly diagonal step. That is unavoidable in a spiral and is one of the genuine reasons to use joined rounds for striped work.

Carry it up, or cut it?

Once you have changed color, you have to decide what to do with the yarn you are not using.

Carry it up the side when the stripe is narrow — up to about four rows. Do not cut. Just leave the old color hanging at the edge and pick it up when you need it next, catching it lightly against the edge stitches as you pass so it does not dangle. Far fewer ends to weave in later.

Cut it when the stripe is wide, roughly five rows or more. Long strands running up the side, called floats, snag on fingers, jewelry, and washing machines, and they pull the edge in and distort it. Cut, leave a six-inch tail, and weave it in.

Never carry a float across the back of the work in ordinary striping. That is a colorwork technique with its own rules; in a simple stripe it just makes a mess.

Joining a new ball of the same color

You will run out mid-project. Same procedure: change to the new ball on the final yarn-over of a stitch, exactly like a color change. It disappears completely because both yarns are the same color.

Two things to avoid:

Do not knot it. Knots work themselves to the surface with use and washing, and they show. Weave both tails in instead.

Do not join mid-row if you can avoid it on anything visible. Run out at the end of a row where the tail can be woven into the edge.

If you would rather not have two tails at all, the magic knot and the Russian join both splice two strands into a continuous yarn. Both are worth knowing. The magic knot is faster and does leave a very small hard point in the yarn; the Russian join is bulkier but completely secure and smooth. Neither is suitable for slippery yarns or for baby items, where woven ends are safer.

Which side does the change show on?

The color change lives in the top of the last old-color stitch. That means the boundary sits slightly differently depending on whether you are looking at the right side or the wrong side, and on tall stitches it can look like the new color bleeds down a fraction.

This is normal and it is how crochet colorwork looks. It is most visible in double crochet and taller, and least visible in single crochet — which is why crisp graphic colorwork is usually worked in single crochet.

The mistakes worth avoiding

Changing at the start of the row. The big one, covered above. Change in the last stitch of the previous row.

Pulling the new color too tight. The first stitch in a new color tends to get yanked snug, which pinches the edge. Deliberately keep it loose for the first two stitches.

Cutting too short. Six inches minimum, longer if the piece will be seamed. A three-inch tail cannot be woven in securely and will pull out.

Weaving ends in along the color boundary. Weave a dark tail through dark stitches and a light tail through light stitches. Running a navy tail through a cream stripe shows through, especially after washing.

Leaving all the ends for the end. Weave in as you go, or a striped blanket becomes a two-hour finishing job you will resent.

Frequently asked

Can I change color in the middle of a row? Yes, same technique. For a clean vertical boundary you will need to manage two yarns at once, which is intarsia-style colorwork rather than striping.

How do I make stripes without weaving in dozens of ends? Use even-numbered stripes so the color you need is always waiting at the same edge, and carry narrow ones up the side rather than cutting.

Why does my color change look like a diagonal step? You are working a spiral in the round. Unavoidable there — use joined rounds for stripes.

Do I change color the same way in every stitch? Yes. Regardless of the stitch height, the rule is the same: the new color goes in on the final yarn-over that closes the stitch.