I am getting ready to start a IM Green Apple Riesling and wanted to know if/when to add a banana. Also, do you just drop a whole banana into the carboy or is there another method?
Why do you want to add a banana to this? I would mush the banana up a bit or lightly boil it in some water and add the water when you mix up the must. 1 banana to a 6 gallon kit is not going to add much if any to the final product. If you are looking to up the alcohol add sugar to get the SG to 1075-1080.
Because its not necessary. Riesling has plenty of body and the green apple is part of the flavoring & sweetening in the flavor pack and that will add a bit of body. Don't forget this is an easy/early drinking type wine, which will be terrific come summer time. I would save the banana for a homemade port or a banana wine. Bet you thought I would say banana bread!
If you do decide to add bananas you'll need more then 1. If this is something you really want to do boil the bananas in some water and use that water as part of your addition to bring the must up to 6 gallons. Make sure you take the SG before adding the sugar because bananas will add to the SG and you'll still want to keep it between 1075-1080.
Also, just a fair warning since I have recently made a mead with bananas, they drop a lot of sediment. So be frugal with your racking and don't worry about leaving behind lees at first because they do not pack well and you don't want to leave any wine behind. Once you add the clearing the sediment will pack down tight and then you can be pickey and top off with a Reisling if necessary.