What you are asking depends on a lot of variables... how heavily the tank is planted, how heavily the tank is stocked, how old the tank is, what your maintenance schedule is, and what kind of substrate you are using. It also will depend on your lighting.
A lot of folks can get away without dosing any ferts with very undemanding plants and low light. Some folks will see a need for adding some trace elements and some nitrogen, maybe some potassium.
What I would recommend is getting a trace mix like API leafzone or Seachem trace.
I would also recommend testing nitrates every week or two, and if you see them bottoming out, consider dosing something like seachem Nitrogen.
You might find some useful info in this article I wrote: http://www.aquariumadvice.com/introd...-planted-tank/