I used the ready made fusible 1/4" green bias tape for stems. It worked great. Clover Quick Bias Fusible Bias tape. It use to be available in many colors. I haven't used any in a long while so hopefully it is still available. I know black and gold are still made, crafters use it.
Another option is the Fast to Turn tubes. It will make the narrowest no raw edge stem to the largest.
https://www.youtube.com/watch?v=HcwZoSH1EyE