I have several ferns whose crowns have gradually built up so that they are now sprouting out 4" to 8" above the surrounding soil. The ferns are still healthy and producing lots of new fronds, but they look a bit funny, so I'd like to replant them deeper if it is practical to do so and not likely to injure the plants. It's a relatively small yard, so raising the soil level in the beds by more than an inch or two isn't really practical. The main ferns with this 'problem' are my Tatting Fern Athyrium filix-femina 'Frizelliae', Holly Fern Polystichum neolobatum, and Crested Soft Shield Fern Polystichum setiferum. The latter two are both 25 years old, very large, and I don't think they have ever been moved. Does anyone know how big and how deep the root ball of such a fern would be? If I was going to reset them, what would be the best time of year to do it - November?, Feb/March? Does it make a difference whether the fern is deciduous like the tatting fern, or evergreen like the other two?