According to a post from user G.W. about growing in Coir:
Recipe
5 gallon bucket
drill a pencil sized hole 3 inches up the side NONE BELOW THIS !!!
rinse coir
mix your coir with 25% perlite and a handful of dolomite
plant your nanner
water with soluble complete ferts @500ppm UNTIL WATER COMES OUT OF THE HOLE
to check water needs simply lift (I kick) the bucket to feel the weight heavy=ok light=add water till it comes out of the hole
hang on to your britches
if you grow tired of your (giant freakin) nanners going all Mary Poppins every time a breeze blows then you can bury the bucket half way in the dirt
it will still drain, although more slowly
If 5gals is too small, then consider a 18 gal or larger rough tote or the like.
Just be aware that coir has huge absorbency and a small plant like 1ft WILL be waterlogged in a container this size. A strong 3ft plant is the smallest I would put in a 18 gal tote.
In a 25 gal I would expect a 15ft+ plant to do fine, maybe only needing watered every other day. The more perlite you add the less water holding capacity.
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So he refers to getting large trees in containers (and smart pots/fabric containers specifically), and I can't imagine it going to 15 ft and not fruiting, but I'm a banana newb.
Link:
Coconut coir