Sashiko needles are longer and thicker than the needles most of us use. This allows for packing several inches of fabric onto the needle at once, a practice that makes the stitching faster and straighter. When I first began sashiko stitching I used needles I had, but invariably they bent and finally broke, so its worthwhile to find yourself a good sashiko needle.
At A Threaded Needle we carry the three types shown here.
Olympus is a good starter package. You get one long and one short needle, both good for comfortably stitching regular cottons and linens.
Clover offers two good quality packages also. I would choose the shorter ones if the idea of such big needles is too much of a jump from what you are used to using. Or if you want to stitch lighter weight threads and fabrics. The biggest needle in this pack will take sashiko thread and #5 perle cotton, so there is lots of flexibility in what you can do with this package.
The Clover long needles are my favorite but I stitch miles of sashiko a month, plus I like to stitch on heavy wool fabrics and on rough linen and hemp. I use the smallest needle in this package for stitching regular weight cotton, and it’s pretty much comparable to one needle in each other the other packages.
Which needle should you choose? It will depend on your project. Most of you will be stitching through one layer of cotton or mid weight linen, and for that I would be inclined to say choose the Olympus package or the Clover short sashiko package.
If you find the longer needles uncomfortable at first, start with a needle you are comfortable with and change to a longer one when you get familiar with
sashiko stitching. The longer needle coupled with the way you pack lots of stitches onto the needle at one time in sashiko stitching both contribute to keeping your stitches straight and even.
Also, If you are stitching a design with long straight lines you will want to use a longer needle, but if you are stitching a design with lots of curves, a flower blossom for instance, a shorter needle may be the better tool.