The usual dose of Osmocote Plus is one capful or 3 tablespoons for a 2 gallon pot. I am going to assume your 9 inch pot holds about a third of the soil that is in a 2 gallon pot so one tablespoon of fertilizer worked into the top one inch of soil would be about right. That said, don't worry too much about getting the exact dose for each container. The slow release formula of the product means the plants take only what they need and you won't see fertilizer burn if you use too much  Osmocote as you would with other plant foods. Keep growing, Marianne Binetti