I seem to have misunderstood the pattern when it came to do the yfwd which meant the original number of cast on stitches wasn’t sufficient for how I understood the pattern. That’s why I modified it slightly: I had 99 stitches per row which worked out fine. I still just did the original number of rows and the cover fits well onto a 45x45cm cushion pad.

A word of warning: you will need more than 1 ball of the main yarn (dark teal). I used 4 (with hardly any left) and even if you stuck to the original number of stitches per row I don’t think 3 would be sufficient.