German Chamomile

Background

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 the 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.

Research summary

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 and 1999 and at the Northwestern Agricultural Research Center (NWARC) in 1999. Research was designed to compare harvesting and distillation methods.

Production from transplants

Chamomile was sown in the greenhouse in 1998 on April 8 and transplanted to the field on May 15, and in 1999 was sown on April 13 and transplanted on May 18. Plant spacing was 8.4" between plants and 18" between rows. Plots were 6 ft x 8 ft, with four replications. Border rows were not included. Plots were split to compare harvesting using a hand rake, which removed only flower heads, with harvest by clipping the plants 45 cm ('Bona') or 55 cm ('Bodegold') from the ground. Harvest by raking in 1998 began on July 10, and was repeated every 10 days until July 30 ('Bona') or August 14 ('Bodegold'), for a total of either three or four harvests, respectively. Raking in 1999 was done at 10-day intervals beginning on July 9 ('Bona') or July 13 ('Bodegold'). Harvest in 1998 was by clipping at 18" ('Bona') or 22" ('Bodegold') on July 20 and was repeated on August 28 for 'Bodegold' only, and in 1999 was done at 10- day intervals on the same schedule as raking.

The two cultivars differed in flowering time and in growth habit. 'Bona' was first to flower each year. In 1998, 'Bona' was harvested three times and 'Bodegold' four. The highest yields were from 'Bodegold' because of the additional harvest. In 1999, both cultivars were harvested four times, with no difference between cultivars in accumulated flower yield. 'Bodegold' had a more upright habit than 'Bona', and may be better suited to mechanical harvest.

Cultivar means followed by different letters are different by LSD (0.05)

Oil was steam-distilled from the plant material in a research-scale still at the Northwestern Agricultural Research Center (NWARC). Oil distillation was not replicated, so data must be considered preliminary. However, a yield of about 3 lb oil/acre could be expected from either cultivar, whether harvested by raking or by clipping. Small research plot yields are normally higher than would be expected from commercial production.

Fig. 1. Cumulative yield of German chamomile flowers harvested by hand raking, Western Agricultural Research Center, 1998 and 1999.

Production by direct seeding

German chamomile was grown in 1999 by direct seeding at both the Western Agricultural Research Center and the Northwestern Agricultural Research Center.

Western Agricultural Research Center

At WARC, 'Bodegold' chamomile was sown at 50 seeds/ft in eight-row plots 16 ft long with 1 foot between rows, in four replications. Plots were clipped twice at 22" on July 21 and August 18, and distilled without drying. On September 1, the remaining plant material was mowed close to the ground and distilled after drying. Border rows were not included.

Northwestern Agricultural Research Center

'Bona' and 'Bodegold' German chamomile were first seeded on May 3, 1999 and failed to establish. Plots were reseeded at a shallower depth on May 27. 'Bodegold' established at 8.6 plants/ft (2.6 plants/m) and 'Bona' at 8.0 plants/ft (2.4 plants/m). Each plot consisted of three 15 ft (4.6m) long rows spaced 18" (46 cm) apart with 3 ft (0.9m) between plots. Experimental design was a two-factor randomized complete block with 4 replicates. Harvesting was done by hand raking flowers or by clipping, and the plant material was distilled fresh or allowed to air-dry. Border rows were not included.

* Distillation on Sept. 1 was not replicated
  
'Bona' was first to flower. Hand raking or clipping was performed on August 3, August 19, and September 3. Plants were clipped at about 18" the first harvest and 24" the second. A final cutting of all remaining top growth was made September 10. 'Bodegold' was harvested August 12, August 26, and September 10. Oil was distilled from the clipped plant material either in a fresh condition or after drying. Raked material was distilled dry. Distillation was not replicated because of the limited quantity of plant material.

Fig. 2. Cumulative yield of German chamomile flowers harvested by hand raking or clipping at the Northwestern Agricultural Research Center, 1999.

A yield of nearly 1500 lb/a of tea-grade flowers was achieved by raking 'Bona' chamomile. An additional 7400 lb of plant material was obtained by clipping the plots after raking them. Tea grade flowers are most valuable as an whole herb. However, clipping the raked plots after the last harvest yielded plant material that could be distilled.

The greatest oil production was from 'Bona', which flowered earliest and was clipped four times. Distillation of plant material of both cultivars after air-drying resulted in a higher recovery of oil than did distillation of fresh plant material, although this needs to be verified with replicated distillations.

Discussion

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.

Acknowledgements

Seed was donated by Johnny's Selected Seeds, Albion , ME.

References

1. Foster, S. 1993. Herbal Renaissance. Gibbs-Smith Publishers, Salt Lake City, UT.
2. Guenther, E. 1948. The Essential Oils. Robert E. Krieger Publishing Co., Inc.
3. Singh, A. 1982. Cultivation of Matricaria chamomilla. In: Atal, C. K. and Kapur, B. M. Cultivation and utilization of aromatic plants. Reg. Research Lab, Jammu-Tawi.
4. Whitten, G. 2000. German chamomile. Tasmanian Herbal 1:44-48.