Icelandic intarsia is an old knitting tradition in Iceland, mostly used in knitted shoe-inserts. It is basically intarsia in garter stitch, displaying brightful patterns in many colors. This unique tradition was unfortunately being lost. My book, Icelandic Knitting using Rose Patterns (Search Press 2008), aims not only to preserve it but also give it a new life.
Rose-pattern insert knitting is worked in the same way as regular intarsia knitting but in garter stitch.
It is easier to follow the pattern knitting in garter stitch because, on the wrong side, colors are knitted in the same way than on the right side (you don´t have to read the chart from left to right on the wrong side).
The new yarn must be on the right side of the color block to be knitted. As the pattern moves to the left, it is knitted-in (shown here on the wrong side).
When the pattern moves to the right, the yarn is left lying across the wrong side, then knitted-in (shown here on the wrong side). To do so, knit every other stitch with the lying yarn. It´s sometimes called weaving in.
It is a good idea to knit in or darn in loose ends regularly while working. Darn ends around the blocks, in one direction, then on the other to be safe.
In some cases, in order to avoid unnecessary loose ends, begin at the center stitch and work the ends individually in both directions.
In order to determine the length of yarn needed, when working a small block of color, wind the yarn as many times around the needle as the number of stitches required.
In some cases, it is possible to work a piece using both intarsia and Fair Isle knitting technique. For instance, the motif is knitted using intarsia technique while the main color is knitted along the whole way.