Slip it out of the container and look over the root mass and rhizomes.
Healthy roots are pearly white, sick ones are brown
My guess is you have a muck soil which tends to go anaerobic which is
unhealthy for roots.
Sharp sand or pearlite will loosen that up.
Repotting might be as easy as dunking the root mass in a tub and
washing free as much of the old soil and making a slurry of new soil to
replace it.
Giraffeman wrote:
Hello

I recently bought a Phyllostachys Bissetii and have kept it in a
container. It was dried out when I bought it but after watering it was
doing really well and putting up lots more culms and lush green leaves,
however, now it's having many leaves turn yellow and not looking as
good.

Does anyone know why this may be? It's been in the same position since
I bought it 3 months ago.

Thanks for any advice.




--
Giraffeman