MULLEIN LEAF: Frontier Co-op Cut & Sifted dried mullein leaves make a soothing herbal tea. HERBACEOUS BIENNIAL: Mullein is a biennial herb, completing its life cycle in two years. SUSTAINABLY SOURCED IN BULGARIA: Frontier Co-op Mullein Leaf is grown and harvested in Bulgaria and is kosher and non-irradiated with no artificial additives or chemicals used in the growing process.