Cymbopogon species belongs to the Poaceae (grass) family. Lemongrass is Cymbopogon citratus. Citronella grass is Cymbopogon nardus.
Cymbopogon includes a number of aromatic perennial tropical grass species with mostly lemon scented foliage. The gray-green stalks are 2 to 3 feet long and are as stiff as beach grass. The plant grows in dense clumps as big as 6 feet in height and diameter. Cymbopogon nardus is the source of commercial citronella oil. Cymbopogon citratus (lemon grass) is cultivated for the edible stem and for lemon grass oil.
In 1988 the U.S. imported 74 metric tons of lemongrass oil primarily from Guatamala and India. The value of this was estimated at $900,000.
Use: Inside the fibrous stem layers of lemon grass is a paler tubular core that resembles a firm scallion bulb. Cooks sliver this more tender part into various dishers, adding a pundent lemon flavor. It's also used in herbal teas, and baked goods. Oil from lemon grass is widely used as a fragrance in perfumes and cosmetics, such as soups and creams.
Climatic requirements: The best climate for lemongrass are temperatures ranging from 64-84˚F, and high humidity (80-100%). However, in Stanislaus county lemongrass is successfully grown in high temperatures (70-100˚F) and low relative humidity (40-60%). The dry environmental conditions of the area favor the growth of the plant but not the growth of plant pathogens which go after the crop in tropical areas native to the species. Lemongrass utilizes sunlight very effectively, therefore it should be planted in areas of the farm exposed to the sun.
Cultural practices: Lemongrass grows best in well drained sandy soils free of weeds and soil borne pathogens such as fusarium and verticillium. Since the plants rarely flower or set fruit, propagation is usually done by root cuttings or plant divisions. Stanislaus county growers place the plant cuttings in furrows 3-4 ft. apart on beds 4-5 ft. wide depending on variety and the duration of the season. Raised furrows are recommended to minimize crown root rot problems which could be induced by irrigation water. Even though lemongrass is a perennial crop in the tropics, conditions of the valley will kill it off with the first freeze. Therefore the crop is planted as soon as the danger from frost is past to prolong the growing season. However, Stanislaus county growers have been observed successfully protecting the crop against cold weather with plastic covers. This enables a harvest during March and April which brings a premium price.
Fertilization: Lemongrass has pretty much the same nutritional requirements as sweet corn. Growers in Stanislaus county applied, on the average, 120-180 lbs. of nitrogen per acre, 140-180 lbs. of phosphorous and some potassium if needed. All the phosphorous and potassium and about 15-20 lbs. of nitrogen are placed 4-6 in. under the plant as starter fertilizer. The rest of the nitrogen is split and applied during the season as a side dress or water run, preferably prior to, or with an irrigation to improve plant uptake.
Irrigation: Lemongrass requires an average of 24-30 inches of water per year, which depends on available soil moisture, soil type and environmental conditions. Irrigation is usually done on an 8-10 day schedule. However, due to the shallow root system of the crop, it is more beneficial to irrigate more often with lighter irrigations. Moreover, the frequency of irrigations will increase the humidity, which favors rapid plant growth.
Harvest: Even though lemongrass is a perennial crop in the tropical areas of the world, in northern California it is seasonal due to the extremely cold weather experienced in the winter months. In Stanislaus county lemongrass is usually harvested once a year, despite the fact that in other parts of the world, lemongrass can be harvested up to four times per year. In the county, harvest is done by chopping off entire plant clumps from the base. Tillers (stems) are then separated from the crown, cleaned and bunched up for immediate sale. Bunches consist of 6-8 stems, but sometimes 4 stems can make up a bunch. A premium is paid for larger, thicker stems.
Taylor's Herb Gardens Inc. 1525 Lone Oak Road, Vista, CA 92084.
Sunrise Enterprises, P. O. Box 10058, Elmwood, CT 06110-0058.
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Prasad, L.K. & Mukherji, S.R. "Effect of Nitrogen, Phosphorus, & Potassium on Lemon Grass." Indian J. Agron, 1980. 42-44 pp.
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New York. Cornell University. 1976. 1290 pp.
The Authors: Jesus Valencia, Farm Advisor, Stanislaus County, and Claudia Myers, Associate Director, UC Small Farm Center.
Figure 1. Lemongrass grows in thick clumps up to 6 feet in height and diameter. (Photo by Charlotte Glenn).
Figure 2. Lemongrass being readied to send to market (Photo by Claudia Myers).
Figure 3. Lemongrass growing in the field (Photo by Jesus Valencia).
Figure 4. Lemongrass under plastic (Photo by Jesus Valencia).