Adding Potassium for Tomato Plant Soil

[NewGardener]

I have a tomato project that I am starting for my Botany class and had heard about how putting banana peels in soil would help the plants grow... I originally thought about chopping up peices of the peel and putting it in around the soil to help the decomposition process; however, upon further research I've read that its best to use the peels in a compost.

I'm trying to find a easier way of adding nutrient/potash to my soil without needing to make a compost being that my plants are already potted. So, I came up with an idea of the possibility of using coconut water (vita coco) as my added nutrient which has high levels of potassium in it.

Can too much potassium hurt? How often would you suggest adding it and how much? And what are your views opinions of doing this? Will putting peices of banana peel in around my soil be enough to effect my plants? I'm new to this and was just trying to come up with a creative variable for my tomato plants, but suggestions are welcome!