Banana Skins are an excellent thing to put in to your composter and a good use of a common throw away item. They are a great source of organic material and valuable nutrients for your compost. Some people cut them up first to help speed up the composting process, others put them in whole, but it really doesn’t matter either way. They will quickly and easily decompose in your composter or compost heap with no problems.
Alternatively, banana peels are an excellent source of nutrients for roses. Some people bury the banana skins a few inches under the ground, around their rose bushes. Roses seem to benefit greatly from the nutrients provided by the banana skins and produce a good healthy show of flowers. And it’s a good simple natural way of fertilising your roses without having to resort to chemical fertilisers.
But if you are doing this, you should be aware that it may take a bit longer to decompose the banana skins if they are buried beside your roses. Decomposition works best and quickest in the presence of air, and burying the banana peels under the soil deprives the decomposing microbes of the essential oxygen. They will break down eventually and release their nutrients, but it may be faster to add them to your general compost heap or composter, allow them to break down, then add the compost to the roses.