Here is how to make a two-color crocheted spiral: begin with Chain 3. (photo above)
Join with a slip-stitch to form a ring.
Ch2, 5 dc into the center of the ring. (i.e. chain 2, 5 double-crochets into the ring.)
Stretch out the pink loop on your hook and remove the hook. Join yellow into the ring.
Ch2, 5 dc into the ring.
Now here is the trick that makes the whole thing work! Wrap your hook once then insert it into the SPACE BETWEEN the first ch2 and the first dc. Complete a double-crochet, then make two more in the same space. This is like working sideways up the first chain-2.
Here is another shot of the 3 dc’s worked up the side (or, into the space between the first ch-2 and the first dc).
Now begin working into the tops of each double-crochet. Notice that sometimes I have made two dc’s in the same space, other times just one. The important thing is to keep your work flat. Until you get used to this, check your piece, often, by laying it on a flat surface. [If it ruffles, you may have too many dc’s. If it won’t lay flat, there may be too few.]
Work dc’s right up to the spot where you dropped the loop of the first color, as shown in the photo, above. Stretch out the loop on your hook, then remove the hook.
Pick up your first color (pink, in my case) and wrap your hook for a double-crochet.
Insert the hook into the space between the ch2 and the first yellow dc.
Work 3dc into this space.
Continue working dc’s into the tops of the previous row’s dc’s – keeping your work flat.
Continue working dc’s up to the last dropped loop (see how the pink dc’s go right up to the dropped yellow loop in the lefthand photo?) When you bump into a loop, drop the color you’re working with and pick up the other yarn.
Continue in this way for as long as you like – work up to a loop, drop the current yarn, pick up the next yarn.
For the sake of brevity, I’ve chosen to end my yellow stripe, here. All I did was to gradually decrease the height of my stitches, from dc to hdc to sc to a final slip-stitch. Then I finished off the yarn .
I finished off the pink stripe in exactly the same way.
Weave in your ends, and you are done!