The instructions in the box chart call for diagonal holding over the colour change area, but as can be seen here the colour change is still quite marked & I wanted it to be more subtle. I decided to borrow a technique that I learned when doing my phase two piece, Kirigami.
Bit odd to describe without photos, but basically it uses two needles, one has the first colour, the second has a mix of colour one and two and you alternate stitching with these needles, gradually fading in the second needle. Fasten off the first colour and then thread the needle with the second colour and then work both needles again, fading out the mixed thread and in the second colour. It looks like this when it's finished.
I didn't use such a long section for the colour change on the leaf, but it's worked much better and I'm much happier with the result.
The calyx on the iris called for variegated colours, so I used a 1.5 thread in random colourways to create the effect.