Tansy (_Tanacetum vulgare_) is a European perennial plant, long
cultivated in this country in gardens, from which it has escaped, and
it now occurs as a weed along fence rows and roadsides. The leaves and
flowering tops are in some demand for medicinal purposes. The herb also
yields a volatile oil, for which there is a small market.
Tansy grows well on almost any good soil, but rich and rather heavy
soils well supplied with moisture favor a heavy growth of herb. It may
be propagated from seed, but is more readily propagated by division
of the roots early in spring. The divisions are set 18 inches apart
in rows 3 feet apart. Seed may be sown very early in the spring in
the open or in seed beds, and the seedlings later transplanted to the
field. Such cultivation as is usually given to garden crops will be
sufficient.
The plants are cut late in the summer when in full flower, the leaves
and tops being separated from the stems and dried without exposure to
the sun, as the trade desires a bright-green color. For the volatile
oil the plants are allowed to lie in the field after cutting until
they have lost a considerable portion of their moisture. They are then
brought to the still and the oil removed by the usual method of steam
distillation.
A yield of about 2,000 pounds of dry leaves and flowering tops per acre
may be obtained under good conditions. The yield of oil varies, but
about 20 pounds per acre is a fair average. In the United States the
center of production of oil of tansy is Michigan, where about 2,500
pounds are distilled annually. The price of the oil in June, 1920, was
about $8 a pound. The price of the leaves and tops usually ranges from
3 to 5 cents a pound.