Q.How much cottonseed meal should I put on potted blueberries?
I have one and blood meal to put on them. Can I use both and how much? They are in big flower pots. How much cottonseed meal and blood and bone meal should I put on my 3 yr. old blueberries that are planted in big flower pots?

A soil test is highly recommended in order to determine your ph levels. Only then can you determine how much cottonseed meal or bone meal you would need to apply.
Here is a link to help you locate your nearest extension service.
https://www.gardeningknowhow.com/extension-search/
Here is also a couple of great articles.
https://www.gardeningknowhow.com/edible/fruits/blueberries/blueberry-fertilizer.htm
https://www.gardeningknowhow.com/garden-how-to/soil-fertilizers/cottonseed-meal-fertilizer.htm