Use a yarn needle (aka tapestry needle) to stitch yarn through two rows of live stitches, making a completely seamless join - step-by-step instructions are given for stockinette or garter stitch live stitches. It may be a little tricky at first, as it feels more like sewing than knitting, but once you get the rhythm of it down, it's relatively easy and so satisfying once it's finished!

Many leethal patterns use grafting; most of them give the step-by-step directions written out within the pattern, for your convenience.

Important for all versions of grafting: as you make the grafted stitches, pulling yarn through the live stitches, pull at an even tension, matching the tension of the knit stitches, for a seamless line. Check how it's looking after you work an inch or so, and tighten or loosen the grafted stitches as you go - if you work the whole seam too tightly or loosely, it can be very difficult to fix it later. I find that I usually need to pull a bit tighter than I think, as my grafted seams are often a tad bit loose if I'm not careful.

grafting stockinette stitch

seamlessly join two rows of live stitches together with kitchener stitch to make an invisible stockinette stitch seam

(2 rows of live stockinette stitches pictured here - in tutorial steps below, "front" stitches are grey and "back" stitches are orange)

holding the 2 rows of stitches together, needles parallel, wrong sides touching, with yarn threaded onto a blunt-tipped yarn needle, bring yarn needle purlwise through first stitch in front

to finish setup, bring yarn needle knitwise through first stitch in back

now begin the 4 repeat steps

step 1: bring through first stitch in front, knitwise, dropping stitch off knitting needle

step 2: bring through next stitch in front, purlwise, leaving stitch on knitting needle

step 3: bring through first stitch in back, purlwise, dropping stitch off knitting needle

step 4: bring through next stitch in back, knitwise, leaving stitch on knitting needle

once you get the hang of it, you can condense the steps into 2 - front, then back

condensed step 1: bring through first front stitch knitwise, dropping it off, then through next front stitch purlwise, leaving it on, then pull yarn through both stitches at the same time

condensed step 2: bring through first back stitch purlwise, dropping it off, then through next back stitch knitwise, leaving it on, then pull yarn through both stitches at the same time

when you reach the end and 1 single stitch remains on each needle, work just the first steps for front then for back - bring yarn through final front stitch knitwise, dropping it off, then through final back stitch purlwise, dropping it off

grafting garter stitch

seamlessly join two rows of live stitches together to make an invisible garter stitch seam

(note: the sides will be labeled as "right side" and "wrong side" to explain the steps, even through the garter stitch fabric will end up looking identical on both sides)

the live stitches may be positioned differently depending on the specifics of your knitting pattern - look at how the purl bumps are positioned on the 2 sets of live stitches, with the needles parallel, looking at the "right sides" (the sides which are held on the outside as you graft, with the "wrong sides" touching)

most likely, the front row of stitches are purl stitches along the top (so the garter stitch bumps are right against the needle), and the back row of stitches (looking at the "right side" or outside) are knit stitches along the top (so the garter stitch bumps are not right up against the needle), in which case, graft as follows - if your positioning is otherwise, scroll down to other options

holding the 2 rows of stitches together, needles parallel, wrong sides touching, with yarn threaded onto a blunt-tipped yarn needle, bring yarn needle purlwise through first stitch in front

to finish setup, bring yarn needle purlwise through first stitch in back

now begin the 4 repeat steps

step 1: bring through first stitch in front, knitwise, dropping stitch off knitting needle

step 2: bring through next stitch in front, purlwise, leaving stitch on knitting needle

(repeat steps 1 and 2 with back stitches)

step 3: bring through first stitch in back, knitwise, dropping stitch off knitting needle

step 4: bring through next stitch in back, purlwise, leaving stitch on knitting needle

once you get the hang of it, you can condense the steps into 2 - front, then back

condensed step 1: bring through first front stitch knitwise, dropping it off, then through next front stitch purlwise, leaving it on, then pull yarn through both stitches at the same time

condensed step 2: bring through first back stitch knitwise, dropping it off, then through next back stitch purlwise, leaving it on, then pull yarn through both stitches at the same time

grafting reversed garter stitch

if your front row of stitches are knit stitches along the top (so the garter stitch bumps are not right up against the needle), and the back row of stitches (looking at the "right side" or outside) are purl stitches along the top (so the garter stitch bumps are right against the needle), then graft the same as above but flipping all knitwise/purlwise, as follows

holding the 2 rows of stitches together, needles parallel, wrong sides touching, with yarn threaded onto a blunt-tipped yarn needle, bring yarn needle knitwise through first stitch in front

to finish setup, bring yarn needle knitwise through first stitch in back

now begin the 4 repeat steps

step 1: bring through first stitch in front, purlwise, dropping stitch off knitting needle

step 2: bring through next stitch in front, knitwise, leaving stitch on knitting needle

(repeat steps 1 and 2 with back stitches)

step 3 (not shown): bring through first stitch in back, purlwise, dropping stitch off knitting needle

step 4: bring through next stitch in back, knitwise, leaving stitch on knitting needle

once you get the hang of it, you can condense the steps into 2 - front, then back (pictured after a few repeats)

condensed step 1: bring through first front stitch purlwise, dropping it off, then through next front stitch knitwise, leaving it on, then pull yarn through both stitches at the same time

condensed step 2: bring through first back stitch purlwise, dropping it off, then through next back stitch knitwise, leaving it on, then pull yarn through both stitches at the same time

other garter stitch positioning

if the front row of stitches and the back row of stitches are the same (on the right sides), both knit or both purl stitches, then you won't be able to graft completely seamlessly; there will be an extra row of knits or purls resulting from grafting

if you are able to knit one more row across one side, then you can work seamlessly as above; if you're unable to do that, then the best option you have is to graft the stitches together so that the purl stitches are on the outsides ("right sides"), and use the grafting stockinette stitch instructions, making an extra row of knits on the "right side" and an extra row of purls on the "wrong side" - it's noticeable to a knitter, but no more so than most other kinds of seaming methods