The hostas / ferns were planted a year ago, so they'll probably get bigger (I think) in a few years, so I'm not sure whether this will be less of an issue then. There's still noticeable space between each plant right now.
I should say my goal is not a full-on hosta explosion -- I like them fine, but I don't really like the look of all-hosta-all-the-time (which is common around here). I'm aiming for more of a mixed woodland look overall. There are tall trees overhead, and dappled shade most of the day.
What I have in there right now are a few hostas, a few painted ferns and lady ferns, a few Jacob's ladders, and a few meadow rue (off to the side a bit). I'm hoping to add some Virginia bluebells. (Any other shade woodland perennials I shouldn't miss?)
But I'm also wondering about tiny woodland flowers that might look pretty in spring while we're waiting for the perennials to come out and play, and would potentially make a nice mass of green that would eventually help keep the random weeds down -- would wild violets work there? Anything else?
I do have some blue muscari and white Thalia daffodils in for spring bloom too, and I LOVE them both.