Q.What To Do With My Heavenly Bamboo?
My Heavenly Bamboo was bought in September last year and survived well in its pot over winter but in March all the leaves fell off, despite watering well. Now it’s just a bunch of bare canes, but starting to show some flower growth high up although still no sign of the leaves returning even in late April. Should I cut the canes down where no sign of fruiting is evident please?

Certified GKH Gardening Expert
My best guess will be that it was overwatered. This will cause an infection which will result in the symptoms that you describe. I cannot confirm this, as your photo did not come through, but this is what it sounds like.
You will need to treat with a fungicide. This article will help:
https://www.gardeningknowhow.com/garden-how-to/info/using-fungicides-in-garden.htm
Here is an article to help you to care for the plant:
https://www.gardeningknowhow.com/ornamental/shrubs/heavenly-bamboo/growing-heavenly-bamboo.htm