Green bracken ferns average 25 percent potash and can contain as much as 55 percent. It possesses advantages over other sources of plant ash such as hardwood due to its high potash yield as a percentage of both dry and fresh mass, abundance, growth rate, and ease of harvesting. Bracken has been recognized as a source of potash since at least the 10th century AD, with numerous references in European texts, typically in relation to its use for soap and glass making. The turn to mined sources of potash in the industrial age ended significant usage of bracken as a source of potash, contributing to its status as a troublesome weed.
