Research Summary

Annual wormwood, also called Sweet Annie (Artemisia annua), is an aromatic plant that has historically been used to flavor beverages. Annual wormwood has traditional use in Chinese medicine, and artemisinin, derived from the plant, has antimalarial activity. An essential oil may be distilled from the plant and aromatic ornamental wreaths are made of the foliage.

Annual wormwood grows rapidly, reaching a height of five to six feet at the WARC. A large amount of biomass was produced, with yield of over 6 tons of air-dry material per acre in 1998. Flowering is initiated in response to short days of 13.5 hours or less. The plant is sensitive to frost, and may be less successful in western Montana in years in which frost occurs in early September. It is not suitable for locations with shorter growing seasons.

Artemisia annua (Johnny's Selected Seeds, Albion, ME) was sown in the field on June 17, 1998, June 11, 2001, and June 7, 2002 at the Western Agricultural Research Center, Corvallis, MT. Six-row plots were 8 ft long with rows 18" apart and variable spacing between plants, with four replications. In 1998, plants were harvested either at bud stage on September 11 or at full bloom on September 21.

Table 1. Harvest date and yield (dry matter, t/a) of annual wormwood planted at different densities
Plant spacing
18" x 8"
5.8 a
4.9 a
18" x 16"
4.4 b
4.6 a
18" x 24"
4.5 b
3.9 a

Means within a column followed by different letters are different by LSD (0.05).


  1. Simon, J.E., D. Charles, E. Cebert, L. Grant, J. Janick, and A. Whipkey. 1990. Artemisia annua L.: A promising aromatic and medicinal. p. 522-526. In: J. Janick and J.E. Simon (eds.), Advances in New Crops. Timber Press, Portland, OR.
  2. Harvesting drugs from medicinal plants. USDA Agricultural Research magazine, April 1998.