I don’t feed our tree ferns – they’re fed by the decaying matter of plants and insects caught in their tops that slowly decomposes. I am greatly in favour of any advice that says “do nothing”. What tree ferns really need is protection from winds, and lots of water, or rather frequent water, but not necessarily very much of it. The brown water from decayed leaves is excellent for this, but not essential. Watering, however, is.
