Posted: 18/02/2017 at 08:59
I don't think that would be big enough GD. You need big enough so that it doesn't feel restricted, and therefore grows properly, but big enough in each direction (especially depth) to contain the roots properly. I'd make something a metre square, or a metre long by 60 cm wide depending on the space you have available, and at least 60cm deep - as a minimum.
If the bamboo doesn't work, you can always remove it and have a planting area that has different conditions from the rest of the area - for instance damp, rich soil if the other bits are sandy, dry and free draining, or vice versa.