Re: Soil drainage
You said: "... a deeper pilot hole under the plant can also be dug and filled with a good draining media..."
The problem with that is, the planting hole will hold water like a bowl drowning the roots. I wouldn't dig more than 6 or 8" inch and re-fill with a well draining soil. If water can't drain though the soil it will be forced to drain to the ground surface. ... Banana roots only grow to about 14" to 16" deep then spread out.