Costmary, Tanacetum balsamita, is one of those herbs that used to be in every herb garden but is now rarely seen. It was used medicinally and like other plants associated with the virgin Mary, was used for women’s issues, mainly to bring on menstruation. For that reason, it should never be used internally by pregnant women. One of its nicknames, alecost, refers to its use to flavor ales and spiced wines.
Its leaves contain fragrant oils making it useful as a strewing herb. The scent is similar to balsam. The oils also keep away silverfish, so costmary leaves were often tucked into the pages of family bibles to protect them from damage during a time when books were expensive. Another convenient use of the leaves as bookmarks was that congregants could surreptitiously sniff the leaves in church to keep themselves awake during long and sometimes boring sermons.
Costmary is a member of the aster family. It is a perennial herb native to the Mediterranean area. It is hardy to zone 4 and while it will do well in regular garden conditions, it prefers to be dry making it a candidate for a xeriscape. Costmary prefers full sun but can tolerate some shade. The plants reach a height of 3’ to 4’ with leaves up to 1’ long and 2” wide. The flowers are small yellow disks similar to tansy flowers. Costmary will only flower if grown in full sun. If grown in shady conditions, it will grow more and bigger leaves. Plants should be divided every 3 years to keep them healthy.
Although most people buy plants, costmary can be grown from seed. Surface sow the seeds. They need light to germinate. Lightly press the seeds against the soil and keep evenly moist, not wet, until germination. Plants can be transplanted into your garden when they reach 6”.
Harvest and dry the leaves from your costmary and use them in potpourri or sachets or to scent your bathwater, alone or in combination with other herbs.