Web Master:
Hi Anna
Brown leaves can indicate a problem with water or over fertilisation.
Birds Nest Ferns need well drained soil with reliable moisture and don't do well if the soil becomes dry.
Worm juice is high in ammonia and can be toxic to plants to it is important to dilute it at least 1:10 before using.
Regardless of whether it is too little water or too much nitrogen, I think your plant would benefit from repotting. You can use the same pot or a slightly larger one.
Firstly, remove all the dead or dying fronds then take the fern out and gently tease the outer roots. Add Perlite to your fresh potting mix a ratio of approximately 1:4 ( this will keep the soil well drained and aerated). Fill the base with potting mix, then place the fern on top and fill around the sides with potting mix. If the plant seems too low in the pot it is best to lift it out and increase the amount of mix at the bottom rather than adding soil at the top around the plant base. Water to allow the soil to settle followed by a well balance fertiliser suitable for ferns. Place in a bright spot protected from the harsh afternoon sun.