Wait for the mullein plant to reach at least two years old. The plant does not flower until its second growing season.
Cut the entire plant off at the base, 1 inch above the soil level, if you also want to use the stems and leaves. Use sharp gardening shears.
Cut the flower stalk off at the bottom of the stalk, just above the leaf formations, if you do not want the leaves. Shake the stalk gently to shake let loose any insects or dirt in the flowers.
Wrap the bottom of the stem in a piece of string and tie a tight knot. Hang the flower stem upside down in a dry, shady place for 4 weeks. The flowers will dry out completely after this time. Pull the flowers off the stalk and store them in an airtight container.