This tutorial shows how to sew together moss stitch (aka seed stitch) using mattress stitch. Mattress stitch is an invisible (from the right side) join between the sides of two pieces of knitting.
You’ll use the running threads between the edge stitch and next-in from the edge. Running threads are the pieces of yarn which connect a stitch to its neighbour. For the running thread join you simply sew under a running thread on one piece of knitting then sew under a running thread on the other piece, working your way steadily upwards.
Here’s the needle going under four running threads.
The same process can be done regardless of whether rows begin or end in knit or purl (see photo at the end for evidence).
Tips for mattress stitch
- To sew up, use the same yarn as you used for the project unless it is very thick yarn.
- Unless it’s just a little seam, do not use a dangling tail in case you need to reknit a bit, you’ll have to unpick the whole seam first. Instead, cut a piece of yarn about three times as long as the length of the seam (longer than for stocking or ribbing as you have to sew up every row).
- For long pieces, use safety pins or butterfly hairclips to align the garment corners and some key points in the middle. When your needle gets to one of these markers on one side you should reach it at the other side on the next stitch – if not, you’ll be ending up with a piece of knitting looking like a shirt with its buttons done up into the wrong button holes. If you do end up a bit skeewiff, do a couple of bars on one side and just one on the other a few times, but spread this out, don’t bunch it all into the next few stitches.
The yarn used here is Hjertgarn Woolcott, a machine-washable 55% lambswool, 45% cotton DK.
You’ll be using the running threads between the edge stitches and the next-to edge stitches. The edge stitches are bit trickier to see so find the next-to-edge stitch column, the running threads coming from that are the ones you want.
First you need to secure your yarn with a figure of eight join. With right sides (RS) up, bring the needle up from back to front by the bottom corner stitch (the first few rows are also often squashed a bit, so find the running thread between the edge and next-to-edge stitch a bit higher up and come out just under the bottom one) on the left side piece of knitting, then reach around the back and come up through the same hole. The yarn is now secured to one piece of knitting. Leave a long enough tail that you can weave it in later.
Now bring the needle up from back to front by the bottom corner stitch on the right piece of knitting. Now up again through the same hole on the left piece. See the figure of eight?
With RS up, pass the needle under the first running thread on the right hand piece (you put the needle in where it came out before). Your needle stays at the front of the work, you never need to pass it all the way through the knitting. Then pass the needle under the first running thread on the left hand piece.
Put the needle back where it came out on the right side and pass under another bar. Put the needle back where it came out on the left side and pass under another bar. Keep repeating this, one running thread at a time.
After a couple of inches, pull the thread taut and the sides will zip up together seamlessly (pull it back if it gets too tight). Then carry on.
When you’ve sewn under the last running bar on the right side and the left side, and pulled taut your yarn, you’ll probably find it looks a bit scruffy. Now you do put your needle all the way through your knitting. If you’ve just done the last running bar on the left then the right, put your needle back where it came out on the left and sew all the way through.
You now have even rows of bumps and hollows all the way along, if the colours were the same, you’d never know there was a join.
The two edge stitches have curled inwards to form a small seam on the WS. Now weave in your end on the WS.
If joining a knit to a knit and a purl to a purl (as you’d often do if your rows have an odd number of stitches), you might want to skip under two rows on one side at the beginning so that when you zip the sides together, you don’t have a purl bump right next to a purl bump. It will still be neat but not quite as seamless. However, the difference is minute – on this swatch half was joined in sequence so the bumps are next to each other, half was a row out so they continue seamlessly. Can you tell the difference?
For a tutorial of mattress stitch on ribbing, see this post on Cut Out and Keep.