If you are using good soil with additional nutrients, you may not even need to use fertilizer. However, it's super easy to apply if you do. Just ensure not to over fertilize the plant, as this could do more harm than good. For example, in a 6" pot, you'll only need around a teaspoon of fertilizer - a little goes a long way! And for a 10" pot, you'll only need around a tablespoon of fertilizer. It's also important that after fertilizing, you water your areca palm well.