If it has the 'potato tuber' type roots held together by either thin roots or string-like attachments, it is most likely a scarce species double as my original red double was.
All I have read about the fernies, and mine have always done very well to prove it, they must be planted in well drained soil in full sun, if possible. My permanent beds are 8 inches deep filled with a mix ratio of about 3 bags of "pure humus", a bag of very sandy potting soil and the equivalent of a 1 cu ft bag of "hardwood fines" which are the screenings of hardwood bark mulch. The latter is probably 75% rotted. I toss into the mix wheel barrow a shovel full of peat moss for acid balance. These are raised beds so the roots are not subjected to soaking in wet clay.
The other tip is do not water the fernies after they go dormant with dead tops. They will rot if left in soaked soil. I think most of them come from very cold, dry winter climates and do not need water.
I like to sprinkle some Miracle Grow wettable fertilizer in the dry power form in the bottom third of the planting hole deep enough to where the new roots do not touch it but as the roots grow, they can find it easily. Then, after planting the eyes no more than an inch deep or even level with the surface, mix up a watering can with about a tablespoon per two gallons of water and water them in until the soil is soaked. After that, Mother Nature will normally furnish all the water they need.
