Burdock (_Arctium lappa_) is a large biennial plant well known as a
common and troublesome weed in the Eastern and Central States and in
some western localities. The dried root from plants of the first year's
growth forms the official drug, but the seeds and leaves are also used
medicinally.
Burdock will grow in almost any soil, but the best root development is
favored by a light well-drained soil rich in humus. The seeds germinate
readily and may be sown directly in the field, either late in the fall
or early in the spring. The seed may be sown in drills 18 inches or 3
feet apart, as desired, and should be sown 1 inch deep if in the fall,
but less deeply if sown in the spring. When the seedlings are well
up they should be thinned to stand about 6 inches apart in the row.
Cultivation should continue as long as the size of the plants will
permit.
The roots are harvested at the end of the first year's growth in order
to secure the most acceptable drug and also to prevent the plants from
bearing seed and spreading as a weed. The tops of the plants may be
cut with a mower and raked off, after which the roots can usually be
turned out with a deep-running plow or with a beet lifter. In a dry and
very sandy soil the roots frequently extend to a depth of 2 or 3 feet,
making it necessary to dig them by hand. After digging, any remaining
tops are removed and the roots are washed and dried, the drying being
preferably by the use of low artificial heat. The roots are usually
split lengthwise into two or more pieces in order to facilitate drying,
although whole roots are marketable.
Yields at the rate of 1,500 to 2,000 pounds of dry roots per acre have
been obtained. The prewar prices offered by dealers ranged from 4 to 6
cents a pound. The prices for the root and seed in June, 1920, were 12
cents a pound each.