woebegonia, I am not sure that a green banana will work. It is during the ripening process that ethylene is produced.
On a plantation scale, as the first bunch ripens the 'ethylene effect' is very slow but as the neighboring bunches "feel" the effect, they in turn, ripen and the process accelerates in geometric proportions.

Thank you for the tip.

That's right. It is already ripe, or at least ripening fruit, that produce the most ethylene in general. I am not sure (never looked into it) that bananas are necessarily the best ethylene producers, but they seem to have been studied a lot.

Do you have bromeliad relatives that you want to induce bloom on? A cut apple in an enclosed environment can do the job too. Remember that ethylene also speeds the process of decay, and may distort growth, so be sure to remove the ethylene source if you see an flower buds at all coming.

Rick

Thanks again.