No soil, no matter how big the pot, will have enough nutrients to grow a plant through the entire flowering cycle without supplemental feeding.
The combination of your plant feeding and water leaching nutrients, will lead to your plants needing extra food at some point.
Surely it is not that hard to mix a watering can of fertilizer every 10-14 days? There are plenty of healthy organic supplements available.
If you are worried about deficiencies, adding something at some point will be unavoidable.
Hope this helps,.........
Organoman.