I make my own soil and compost mixture and I am lucky enough to live where I have many banana trees. I have found that using banana parts in my compost is very useful. As JC stated no citrus especially if you are putting them directly into your container. If you can make a little space for composting some materials even in a 5 gallon bucket with lid you will find your grows much better, require less work and less purchased food for them saving you mega dollars in a short period of time.