The trellis pattern is excellent to use for warm garments like this winter hat. Here I have made the trellis pattern by knitting one stitch, lifting three stitches (with yarn in front), knitting one. Next row is knit, then the third row is the same pattern but shifted two stitches. The most important part is to include the loos strand from two rows below into the stitch, making the diagonal effect!
It can be done in different combinations and makes nice effects; you can use it with only one colour or different like I did for this hat. This one was intended for my husband, but it ended up bigger (…did not check my gauge properly!), so it ended up as mine! A good thing – I almost never knit anything for myself.
Here is a description of the technique:
First, slip three stitches and be sure to keep the strand (here in blue) in front. The fourth stitch is in the middle of the loose strand made two rows ago.
When knitting the fourth stitch, include the loose strand below by lifting it by the right needle before inserting the needle as usual into the fourth stitch. Then knit the stitch as usual. This is called k1 uls (knit 1 under loose strand).
Continue by lifting the next three stitches, and make a new k1 uls in the fourth stitch.
Knitting on circular needles means that you will let the yarn stay on the outside of the work when you are done with the trellis row, and the last loose strand will be more horizontal than diagonal. The last strands for each row ends up a bit more horizontal than the others.