When I had a 29 gallon tank I had 3 sword plants in it, with water column fertilizing and inert substrate - no root fertilizing. It was a high light setup with pressurized CO2. Within about a month one sword virtually filled the tank. I removed it. Another month and the other two swords filled the tank. Never any root fertilizing.
I concluded, and later found that I was correct, that the sword plants can feed from either the leaves or the roots or both. In fact virtually all plants can do that.