The half double crochet (abbreviated hdc) is kind of an oddball stitch. The half double crochet falls in between a single crochet and a double crochet in height, but instead of working off two loops at a time, you draw the yarn through three loops on the hook. It produces a fairly tight fabric similar to one made with a single crochet stitch:
1- Do 15 chain stitches (ch 15).
This step creates the foundation chain.
2- Chain 2 more stitches.
These stitches create the turning chain.
3- Yarn over the hook (yo) and insert your hook in the third chain from the hook.
You should have 3 loops on your hook.
5- Yarn over the hook and draw your yarn through all 3 loops on your hook.
This step completes a full row of half double crochet stitches.
7- Work 1 half double crochet stitch in each successive chain across the foundation chain.
You have 16 half double crochet stitches at the end of Row 1 (counting the turning chain as 1 half double crochet stitch).
8- Turn your work.
You need to turn your work to start Row 2.
9- Chain 2 (ch 2) and yarn over the hook (yo).
The two stitches are for the turning chain.
10- Skipping the first stitch of the row directly below the turning chain, insert your hook in the next stitch.
Skipping the first stitch maintains a consistent number of stitches per row.
Follow the steps from pulling the wrapped hook through the center of the chain stitch to drawing yarn through all 3 loops.
12- Work 1 half double crochet in the top chain of the previous row’s turning chain.
You should have 16 half double crochet stitches in Row 2 (counting the turning chain as 1 half double crochet).
Repeat the preceding Row 2 steps for each additional row of half double crochet. Continue working rows of half double crochet until you feel comfortable working this stitch.