Many eons ago I happenchanced to become the custodian of a number of staghorn or elk ferns. And way back then, one of our esteemed members here (Essured) told me that her mum ‘feeds’ her stag ferns with banana skins chucked on the top. I have followed those instructions religiously since, and my ferns are thriving.
Which brings me to the question, why banana skins? What nutrients do the skins provide, why are they so effective, and what the hell is happening?
Potassium is used as a fertilizer, could be that?
Also the skins would hold in the moisture, very important.
Yeah, I thought about the potassium thingy, but I’ve never heard b/skins recommended for any other sorts of plants, just the epiphyte ferns.
And the other thing is that they dry out really quickly too…in Melbourne, humidity is mostly lacking so the moisture-retaining aspect doesn’t work either.
I’m sure it’s some sort of witch’s magic spell or something. 
I wonder if the banana skins give off much ethylene, and if ferns would respond to it. Ethylene is a plant hormone best known for stimulating the ripening of fruit, and whole bananas emit a fair bit of it, but ferns don’t make fruit, so I couldn’t say what it would do to ferns. Maybe the skins just make good compost.
Sounds like a marvelous way to attract fruit flies.
And when the banana peels dry up, you can smoke 'em.
Just look up how they absorb nutrients. Many air plants feed off of insects and bannana peels would attract some bugs.