I’ve used this method before too...I also have a couple different sizes of Clover bias tape makers and hey make great stems which can either Nobel machine sewn or hand sewn onto your project.

If they are curvy, you should use bias strips, but if they are short or straight, using the straight grain will be fine. I cut mine around 1" and fold them in thirds as you mentioned. I iron them well (a dab of glue helps hold the flaps down) and either hand applique (not difficult - just like sewing binding only a little finer) or use a regular sewing machine stitch in matching thread on each side. You can go wider or thinner than 1".

Clover bias tape makers are wonderful - a worthwhile investment - easier to use than bias bars in my opinion. A little bit of glue and then appliqué. I prefer to hand appliqué but there’s no reason you cannot machine sew down like you do the flowers and leaves. Lovely quilt.

I've tried machine sewing them and hand sewing - both are awful LOL ... I'm done with it for now ... might give it to someone who wants to finish the stems off and they get a nice lap quilt in the process for all their hard work!