This herb is of the mint family, having downy leaves and small, whitish flowers, and containing a bitter, medicinal juice that is used as an expectorant, vermifuge, and laxative. Cultural: Plant the seed three weeks before your last expected frost date. The seeds are surface sown and covered with a dusting of soil to prevent the wind from taking them. Even moisture is important to encourage sprouting which is erratic. Seedlings are thinned to 10 inches apart and you can harvest the leaves after the plant flowers.