Verbascum Yarrow Click here for a printer friendly version of this page. The foliage of this unusual herb is similar to that of an iris.
Sweet flag is propagated by rhizome division.
This is best done in the spring and fall. Rhizomes should be lifted in the second or third year. If left longer they may become hollow. Harvest the leaves and hang to dry in the fall. The fragrance intensifies during the drying process.