Can you take a stem from a gardenia bush and transplant it ?

I belive so. But, it would be much easier to air layer it. My favorite choice is to, leave branch intact, nick it a little, and bury it underground, it will root.

I agree with Philip. I've done that with many different plants and it nearly always works.

Gardenia cuttings can work, I have some shrubs that were started that way.

Air layering is a little different from what Philip described, which is ground layering. Either could probably work but when I tried to ground layer one Gardenia stem, it never did take root & I gave up after about a year.

They are generally too stiff to bend to the ground without breaking. Bending as far as the soil surface in a pot might be easier. Lay a rock on the point of contact with the soil, so it stays in place.

Purple !
I was talking two different methods or rooting. Air layering and ground layering, are two different methods.
😎😎😎

Philip, "air layering" is where you leave the branch up in the air, nick it and wrap the nicked area with moss or something in a plastic for a few weeks, hoping it will form roots. Then you cut it off and pot it up.

Bending the branch to the ground as you described is known as "ground layering", or just "layering".