My first planted tank was a 20g with a single 24w light and fluorite substrate. I tried out the "natural aquarium" style with minimal fish and minimal effort and easy plants (Vals, a Crypt, and Wisteria). The Vals grew like mad, the Crypt melted and grew back slowly. The Wisteria failed in the 20g but did very well in an Eclipse 6g. That's about as simple as it gets.
Plants are just like animals in that they eat, drink and breathe. They eat dissolved minerals from the water. They drink the water in the tank to keep their cells hydrated and use in chemical reactions so they can grow. They inhale CO2 and exhale Oxygen. They all need the same nutrients, but in different proportions. There's no way to know what your plants will need until they are in your tank, with your water conditions.
So, I think the best advice is to plop some plants in a tank, give them some root tabs and light. If they grow well, great. If not, add a little of fertilizer or a little CO2, see what happens.
A
I really love plants.