Knitting the double seed stitch is like creating a hybrid of seed stitch and moss stitch.
Knits and purls are worked in pairs, then alternated every other row to create neat little squares of knits and purls.
Seed stitch vs. double seed stitch
In the swatch above, the top of the knitting is seed stitch. Knits and purls alternate across each row and alternate up and down the rows vertically.
Double seed stitch, seen on the bottom of the swatch, is kind of like an extended version of seed stitch. Knits and purls are worked in pairs (K2, P2 instead of K1, P1) both across the row and vertically up and down the rows.
Double seed stitch is totally reversible, so it's perfect for things like scarves that show both sides of the work. It won't roll in on the edges like stockinette does, either, so that's yet another benefit.
Double seed stitch pattern
Here's our double seed stitch pattern. (We'll go into detail in the tutorial, but you can use this as reference once you see how it works.)
Multiple: 4 sts
Rows 1 & 2: *P2, k2; repeat from * to end of row.
Rows 3 & 4: *K2, p2; repeat from * to end of row.
Repeat Rows 1–4 for the double seed stitch pattern.
Double seed stitch knitting tutorial
Let's break down the pattern one step at a time.
Cast on a multiple of 4 stitches. So you could cast on 4, 8, 12, 16, etc. Here I cast on 16 stitches so I could get a nice big swatch.
Bring the working yarn to the front. Purl the first two stitches.
Bring the working yarn to the back to knit the next two stitches.
Repeat the P2, K2 all the way across the row. You should finish on a K2. (If you didn't, you either cast on the wrong number of stitches or you missed a knit or purl somewhere! Just count your stitches and double check.)
Row 2 is exactly the same as the last row. Purl the first two stitches.
Knit the next two stitches.
Notice that you're purling the purl stitches and knitting the knit stitches. (If you're not sure how to tell the difference between the two, see the last section of this post.)
Continue working across the row, alternating P2 and K2. You should finish up the row once again with a K2.
The next row changes things up just a little. This time we'll be knitting the purl stitches and purling the knit stitches. So knit the first two stitches.
Purl the next two stitches.
Repeat K2, P2 across the row, ending with a P2.
For Row 4, repeat Row 3. Since we want Row 4 to be identical to Row 3, we're going to knit the knit stitches and purl the purl stitches. So knit the first two stitches.
Purl the next two stitches.
Repeat the K2, P2 all the way across the row, ending with a P2.
You've completed one repeat of the double seed stitch. Hooray!
Now we're going to start with Row 1 again. In Row 1, you'll knit the purl stitches and purl the knit stitches so that you can start your next group of knit and purl pairs.
Identifying knit and purl stitches
The key to the double seed stitch is knowing when to knit and when to purl. If you can learn to read your knitting, you'll know what to do even if you stop in the middle of the row.
Knit stitches look like little Vs. When you're working Rows 2 and 4 of double seed stitch and come across a knit stitch, you'll knit it. When you're working Rows 1 and 3, you'll purl the knit stitches.
Purl stitches look like they have scarves around their necks. When you're working Rows 2 and 4 of double seed stitch and come across a purl stitch, you'll purl it. When you're working Rows 1 and 3, you'll knit the purl stitches.
Identifying the stitch will be really helpful once you start knitting the double seed stitch.