Newfoundland does not exactly have a long growing season. I doubt if they got much “bud” out of their plants. That’s why I am still thinking rope.
During the later centuries of the Viking age, the climate was warmer and as a consequence, farming took place at higher latitudes and altitudes than are possible today. Abandoned medieval farmsteads have been found way up in the mountains and/or up north in Scandinavia in places where the medieval methods and technology hasn't worked since.