Mint Geranium Tanacetum balsamita

Costmary is an aromatic perennial herb with rhizomes and has been used for medicinal and culinary purposes. In the past, it was frequently grown in herb gardens. It currently appears to have grown out of favor. The herb grows erect, about 3-6 feet tall, and emits a mild balsamic scent. The flowers are yellow and button-like that typically bloom from September to October. Costmary is a member of the Asteraceae or Aster family.

The plant is native to Southern Europe and Western Asia. In Europe, between the 16-18th centuries, Costmary was used as a diuretic, laxative, and antipyretic. The herb was used in making potpourri and was tied in bundles with lavender to add fragrance to bedding. 

The genus name, Tanacetum, is derived from the Greek word, "Athanasia," which means "immortal." The species name, balasamita, is from the Latin word "balsamum," meaning "an aromatic resin used for healing wounds and soothing pain. The plant has a variety of common names. The name, Costmary, is derived from the Latin word, Costus, which is an Asian plant used as a spice and preserve. "Mary" references the Virgin Mary and may be related to the plant being used as an herb during Medieval Times to relieve pain during childbirth. It is also known as the Bible Leaf or Bible Plant. Reportedly, American colonists used the long balsam-scented leaves as bookmarks in their Bibles. The scented leaves were pressed in their Bibles to help keep parishioners awake during sermons. The name, Alecost, is derived from the English who used the herb to flavor their ales.

Costmary prefers full sun to partial shade. The plant will produce mostly leaves and no flowers if grown in the shade. It has a shallow root system, prefers well-drained soil,  moist to dry. The plant may become aggressive and crowd out other plants. Clipping or pruning is recommended to prevent it from becoming leggy and to increase foliage. The plant may be propagated by root cutting, stem cuttings, or division. It is not typically grown from seeds due to difficulty with germination.

The leaves are silvery green with a minty balsam scent. They measure 4-8 inches long and oval to elliptic with dentate margins. The flowers are small yellow button-like blossoms and appear in 3 or more corymbiform arrays. The fruit is a tiny achene with a pappus crown.

The plant is pollinated by insects.

Costmary may be used as a fragrant hedge in an herb or perennial garden or a container. The fresh leaves may be used to make tea or add flavor to salads. The leaves should be harvested as needed.  The plant will die back during the winter in colder climates and will resprout in the spring.

Quick ID Hints:

• Leaves silvery green with a minty balsam scent
• Small yellow button-like flowers blooming late summer to fall
• Typically grows 3-6 feet tall and erect
• Fruit is a tiny achene with a pappus crown

Diseases, Pest, and Other Plant Problems:

Costmary does not have any serious disease or pest problems.

The Clemson Cooperative Extension Home & Garden Information Center has a factsheet on common pests and diseases.