Thank you for your replies.
dyzzypyxxy, the cottage is north of Plevna, Ontario. We are new to the lake and have no immediate neighbours. I haven't measured the humidity, but it must be quite high since we require two dehumidifiers on the lower level.
I have already planted some groundcovers, but not in the forest. Let's see, I planted Ajuga Reptans, which didn't last very long. sooby
, I planted Lamium maculatum (Dead Nettle), and it's still hanging in, but not doing too well. The two that have relatively thrived are Japanese Spurge and English Ivy. Perhaps I will get more of those next season.
dyzzypyxxy, I was thinking of trying Periwinkle next spring, as well as Boston Ivy. I'll plant some in the forest as a trial.
One plant that grows very well on the property, though not exactly in the forest, is Eurybia macrophylla (thanks to XiaoLong
, who identified it some months ago). I could try transplanting some of it to the forest sections. It doesn't mind dead-leaf cover, but I'm not sure if it can endure full shade, as all of what we have is growing in at least partial sun.