Osmunda Regalis question

Hi folks, after some research on suitable plants I am looking at adding Royal Fern (Osmunda Regalis) as a marginal. My research suggests it'll thrive in the pond margin but I can't seem to find any info on how to introduce it to the margin. The plant I am going to buy from the nursery is potted normally so can anyone advise on the proper method, if there is one, of acclimatising a Royal Fern to underwater conditions?
Cheers