I took some scraps and developed a prototype leaf, experimenting with different ways to overcast the edges. It’s hard to make out the distinctions in the photos, but I’ll explain.
- Turquoise: hand overcast with the same rayon embroidery thread used for the veins
- Magenta: hand overcast with a matching sewing thread (i.e. matte, not glossy)
- Green: machine zigzagged in matching sewing thread, and then trimmed back to the stitching
- Royal blue: machine zigzag over a cut edge with matching sewing thread
- Orange: machine zigzag in a matching rayon embroidery thread, then trimmed back to the stitching.
And since the look against a green background is irrelevant, here is what it looks like in situ:
In a weird way I feel like the top fabric of the leaf should be folded over the edge of the bottom fabric and appliqued in place on the back, so that there’s no edge stitching showing at all on the front.
I think you should consider a blanket stitch for your appliquÃ©d piece. Google blanket stitch edge for images.