I added a lot of soil to a low area in a bed last spring
that holds too much water. There is a very slight slope across the whole bed,
but I have some “dips”. I lifted the plants and re-planted them afterward.

Now it is low again. I don’t know if the soil settled or
washed out over the course of the winter. Maybe some of both. Other perennials
added late in the season at the edge have some roots exposed on the interior, low
“basin” side.

Will the ferns tolerate just adding more soil, or do I have
to lift them yet again?

If it’s a washout, I don’t know how I can stop this
from happening again. A physical barrier would look unattractive, and I don’t
really want to hold water in, just soil. Thanks.