Question
I am diveing several later this year and want to know the best mix to pot them in?

Answer
Ferns are very versatile and there really is no "perfect" mix.  I would say that the best mix would have a combination of aeration and water-holding capacity.  The most important thing is that the mix does NOT contain and pre-blended fertilizers.  A good mix would comprise primarily of Canadian peat moss (at least 50%-60%) and may include composted bark, perlite, and/or vermiculite.   

In addition to not having any pre-blended fertilizers in the mix, I would not fertilize for the first 6-8 weeks in order to encourage the fern to root and 'search' for nutrients deeper into the new mix.

If you are still deliberating, feel free to send me photos from the labels that you are considering so I can make a more specific recommendation.  I usually respond within 24 hours or so.

Thanks;

Dan