Yes...9 cm is equal to almost 4". Please do consider snipping off the tap root and nipping the terminal apex at transplant to encourage caudex and root fattening, as well as branching. Here's a video that helped me:
https://www.youtube.com/watch?...
I used the disc on only two of my adeniums. There is a definite difference using the disc. I'll explain later. Best to transplant without the disc, though. But experimenting is a good thing!
