German chamomile (Matricaria recutita L.) is an annual plant that is native to Europe. It has been cultivated in North America for many years as an herb or an essential oil. A related perennial species, Roman chamomile (Anthemis nobilis L. or Chamaemelum nobile L.) has similar uses. Both species have white, daisy-like flowers, but the flower receptacle of German chamomile is hollow while that of Roman chamomile is solid.
The flowers of German chamomile are used in herbal teas and extracted for herbal shampoos and cosmetics. An essential oil, used in cosmetics, perfume, and as a flavoring for confections and beverages, may be distilled from the flowers. This oil is called "blue chamomile" because of the compound chamazulene which is formed during the distillation process. Distillation is difficult because of the high boiling temperature constituents, viscosity and other properties of the oil (2).
German chamomile is relatively easy to grow but prefers cooler climates. Chamomile may be cultivated from seed by transplants or by direct seeding. Irrigation is usually needed, especially during seedling establishment. Transplants may be spaced 8" apart in rows 18" apart. Chamomile is seeded in early spring, and seedlings will tolerate a light frost (1). The direct seeding rate is 4.5 oz/acre (0.32 kg/ha). The seed is small and must be planted shallowly. Succession plantings may be made to spread out harvest. Hand harvest for the highest quality (tea grade) product involves raking the flower heads from the plants at intervals. The flowers must be dried carefully to avoid discoloration or heating. Clipping the flower heads from the plants may be an option for oil production, but a lower quality oil results if too much foliage is included. German chamomile will reseed and may become weedy.
Two cultivars of German chamomile, 'Bona' and 'Bodegold' (Johnny's Selected Seeds, Albion, ME) were grown at the Western Agricultural Research Center (WARC) in 1998 and1999 and at the Northwestern Agricultural Research Center (NWARC) in 1999. Research was designed to compare harvesting and distillation methods.
German chamomile is well suited to the irrigated agriculture and climate of western Montana. Reported yields of chamomile flowers range from 3500-4000 kg/ha fresh flowers (approximately 780 - 890 lb/a dry, with a maximum of 1700 lb/a) in India, to 0.1-0.2 kg/m2 (890-1785 lb/a) dry tea grade in Australia (4), to 400-600 lb/a dried flowers in Hungary (2), and 300-500 lb/a dried flowers in northern Europe (1). Small plot yields such as reported here are often higher than those achieved under actual commercial conditions.
While oil distillation was not replicated in these studies, oil production of at least 3 lb/acre was obtained at both the WARC and the NWARC by either clipping or raking in 1999. We expect that a minimum of 3 lb oil/acre could be expected under western Montana conditions. Distillation of German chamomile is difficult because of the viscosity of the oil, and we believe higher oil recovery could be achieved by refinement of the distillation process.
Hand harvesting of chamomile flowers is extremely labor intensive. In Australia, up to 1 kg dry flowers (2.2 lb) could be harvested in an hour, but the average was 0.3 to 0.5 kg (0.7 to 1.1 lb) (4). At the WARC, research plots were harvested at the rate of about 1.35 lb dry flowers or 288 ft2 per hour. The amount of labor required to harvest a field every 10 days or so must be considered when deciding whether to grow chamomile.
Mechanization of flower harvest is not yet common in the US. Harvesters have been designed and built but are not commercially available. The plants grew quite uneven with repeated raking, making it more difficult to reach the flowers lower in the plant. Shearing the plants resulted in regrowth of the flowers at a uniform height at the clipped surface. A combination of clipping and raking may be most useful if a grower wishes to produce both an essential oil and a dried tea-grade flower.
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