I bought a musa zebrina with 3 plants in a small pot about 4 months ago. I replanted into a larger pot with alot of Orchid mix so that the soil would be really well draining. The orchid mix that I got had alot of charcoal wood in it so this helped with the drainage. After four months the plant has grown huge amounts and there are now 7 bananas instead of the original 3. So in my case the charcoal has not affected the plant badly in any way. Maybe there are some other factors affecting yours.

Also, I have never had any luck with basjoos for some reason. Everyone says how great they are and I've had two plants and both have grown for maybe a week after purchase and then just stopped altogether. One was possibly from to o much water even though it was outside, and the other I have no idea why it stopped growing.

I use charcoal in every banana I have re-potted. It helps keep the soil sweet and also helps to deter soil microbes. Stay the course. Charcoal on the surface should not hurt them at all, unless it was from treated lumber or something containing chemicals....

Okay, maybe I jumped the gun.

Two new leaves and starting to grow rapidly. Maybe the deluge of rain (5" in 2 hours) stunned it. But now, watch out world, here comes a tropical banana in the North.

We had a very cool, wet May. Not to the liking of many tropicals and subtropicals. I suspect we just need a good stretch of warm weather with warm soil to get our bananas going.

My brugs have really sulked this Spring and early Summer.