Each species of fern has different requirements regarding is soil. Unless you want nothing but sword ferns under your deck I would keep an eye on it. Sword fern, Nepholepis(sp) will overpower anything else you plant there. First ensure good drainage. Take a bucket full of existing soil to a good nursery. Not Home Depot or the sort or a garden club and let someone with experiance look at it. My soil has a lot of clay in it, so I add coarse sand and peat moss. In areas where I'm growing Adiantum or Pteris I add crushed limestone. And I add Ironite.

Thanks. I will get my soil looked at..... I love sword ferns though they are VERY large and tough. My usual approach is to research a bit, then try what works, then work around what works.

Again thanks for the response. Cecile