Making a trim lie flat

I’m passing this question on for my Mum, but since the jacket she’s knitting is for me, it’s very much in my best interests to get good advice for her, so please help! She has knitted Rowan Classic Reminiscence ‘Boulevard’, designed by Martin Storey, and is just getting to the end of the edging, which is knitted separately. I don’t know quite how to describe the edging, so I’m going to note down the 4 row pattern in the hope that that will help:

Using 3.25mm needles [the yarn is DK], cast on 3 stitches
Row 1 (WS) P3
Row 2 K1, yfwd, K1 tbl, P1. 4 sts
Row 3 P2, (K1, P1) twice into yfwd of previous row, P1. 7 sts
Row 4 Cast off 4 sts (one st on right needle), K1 tbl, P1. 3 sts

My Mum actually used 3mm needles, because when she tried 3.25 she thought it was a bit too big and clumsy, but we aren’t sure whether that’s because of the pattern or the yarn she’s using, so the edging she has done may or may not be tighter than the pattern expects.

The pattern advises you to ‘ease trim around corners so that trim lays flat’. Does that suggest that she should keep it quite loose?

Maybe this is a daft question and there won’t be any issue, but my Mum is quite worried about it (especially since the trim took AGES for her to knit and has been quite frustrating, I think). Any suggestions would be gratefully received (OK, well, any polite ones, anyway!).

Thanks

If the trim is to be sewn on, that’s what is meant by ‘ease trim around corners’ - to make sure it’s not pulled tight around them while attaching.

Thanks, Suzeeq. Should it also be kept fairly loose along straight edges? Is there anything else we should do to help keep it flat?

It shouldn’t curl up, it’s only a few sts and they seem to be sort of a rib pattern. You don’t want it too loose on the straight edges, that may make it ruffley.