If these are the common Bird's Nest ferns-Asplenium nidus it sounds like their not getting enough water it might be the case given the pale fronds. They are epiphytic ferns native to the rain forests of SE Asia and need a constant but not wet potting soil that drains well. The soil should be a good potting soil rich in organic matter. In the temperatures you've given 70s and 80s the soil is probably drying out quickly especially if their pot bound. They also prefer bright light not deep shade to grow well early morning sun is ok too. In winter if grown inside direct sun is best.

Scott

Miracle grow means they are probably too wet, not too dry, that is not a good mix. Can you replant in the garden but first amend the soil with something like the miracle grow, but then mix with your native soil? You can try to make al's gritty mix. But, I think they like the ground better if you have a some shade in Texas. I have a box with with a fern sand clay compost and peat moss, but in a pot you don't want any compost. Birds nest ferns may be hard to grow, I had one once it did not make it. They do well in green houses. This is just general advice. In the house could be too dry if the air conditioning is drying things out.