Boston Fern crispy leaves

A firm crown with green inner fronds or new fiddleheads can regrow after a dry spell. Wholly crisp fronds are dead tissue and will stay brown.

Rewet a dry root ball fully

Water slowly. If the mix has shrunk and water bypasses it, soak the pot from below until the center accepts moisture, then drain. Resume watering as the surface begins to dry; keep the root ball from becoming a hard dry block.

Move the fern away from heaters and hot sun. Cut fully brown fronds at their bases, keeping mixed green fronds. With fewer living fronds, the pot can dry more slowly, so check it rather than repeating the old interval.