If you make a Boston Fern happy, it will fill any pot you give it in record breaking time. The key to success is good light and lots of water. If its only in a 2 inch pot, I would move it to a 6 inch pot. Normally, you would move it up one pot size but with a Boston Fern, I think you would be repotting before the end of summer. Also, they are easy to divide so you can keep it at a reasonable size.
Ok, just found the answer. The arial roots are not arial roots, they are runners. If they were on soil, they would root and grow new plants.