i was talking about this with my LFS owner yesterday. he has these beautifull planted tanks in his shop.
i currently have a 20gal with very low wattage lighting and a java plants that can survive in this condition. they have all survived but grown very slowly.
i thought i knew what i was doing....basically. i'm about to upgrade to a 45gal tank and have decided to establish it heavily planted. i found out yesterday i have alot to learn...
here is what i found out. there are different types of plants. some as mentioned above get nutrients from the water mainly and use roots just to hold on. a small gravel size (1/16" to 1/8") aquarium gravel is adequate for these plants. they require nutrients to be added to the water to thrive. i wont say survive because i have never used any for my java plants and they seem ok....not really doing much....but alive and green.
the second type of plant uses its roots to get its nutrients mainly from the soil. these plants require a special type of soil and the soil has to be enriched with nutrients on a regular schedule. some soils like 'Amazonia Aqua Soil' come pre conditioned with nutrients but eventually will have to be enriched. he mentioned enrichment tabs as the other poster above did.
the other two important things, that i have figured out so far are lighting and CO2. the lighting i had figured out. i bought
http://ahsupply.com/36-55w.htm these light to get my watts per gallon around 2. for most plants i have determined from reading that 2 watts per gallon is a bare minimum for them to thrive and grow half way decent. even at 2 watts per gallon i will have to be somewhat choosie as some plants wont do well even at that. 3-5 watts per gallon seems to be a bit more ideal.
the other thing that was stressed is CO2. this waas new to me and i cant offer any advice other than you might want to look into it. i was told a decent CO2 setup will run $180+ so its something i personally will have to put off for a while. it was mentioned CO2 could be added in other ways but i might have misunderstood this point.....i wasn't to sure how.
you can have a planted tank without an expensive CO2 setup and your plants will survive. there is a difference it seems between a tank with it and a tank without it though. what that actually means for a plants chances of surviving or how fast they will grow i dont know.
from one noob to another i hope this helps some. i'm sure many others could elaborate alot more.