I really haven't tried to investigate the science behind the success of gramma's advice, so I can only offer more details on "what" but not why. She gave it in regard to rose bushes but it seems to have a worthwhile effect on plants that should be blooming but aren't (right time of year, not too young, weather is not unusual, not too wet or dry, other plants of same kind in immediate area are blooming, that kind of "should be blooming.")
I've always felt rewarded by any form of banana use regarding plants. The "whole treatment" is what I did for the bulb, 1 or more entire bananas, laid on the soil surface near the base of the plant. Usually we eat the bananas & plants just get the peels but I forgot how quickly bananas turn when it gets hot and nobody wanted to eat those that were given to the bulb. In retrospect, the unbridled enthusiasm of that banana purchase could have been the work of a vibe from the bulb.
Pureรฉing peels &/or the insides of bananas and putting it in the water given to thirsty plants is another way to share it with more plants, especially if one is squeamish about attracting a few fruit flies for a couple days until the banana material is baked to a crisp by the sun. Highly diluted banana water is unlikely to attract any fruit flies, IME. I see anoles eating them, my little pest munching buddies, & I'm good with that.
