Boston ferns can go downhill fast if allowed to dry out. But they will often come back pretty rapidly if given enough water, although their appearance may suffer for a while :-)

I'd soak the rootballs in a bucker of water for the better part of a day or so, trim off all the dead or dried up portions and re-set your watering system to the proper sequence. If the pots have not been tended to for a couple of years, you may need to repot with fresh soil but if this is the case, I'd wait until the plants look like they've recovered first.

And anything grown in a container will need frequent attention with fertilizers. Again, I'd wait until they have recovered before fertilizing now. The fish emulsion or any other liquid fertilizer will work fine.

Thank you so much!! This is super helpful. We took the plants out and repotted them about a year ago. In that case, do you think the soil is fine, or should I repot with fresh soil? If you say yes, I'll definitely wait to do that (and fertilize) until they're recovered.

I'm so relieved to hear the ferns may survive and even thrive :) Will soak the root balls tomorrow. One question on that - when you say to trim off all the dead or dried up portions, I'm assuming you mean of the leaves/stems? Or would that include the roots too?

Did you divide the ferns when you repotted them? If not, they would certainly appreciate it.