Cymbopogon martini sofia

Cultivation Details

Gingergrass is a plant of the semi-arid to moist tropical and subtropical lowlands^[1]. It occurs naturally and in cultivation in India from 12 - 32N and has been grown successfully from between the latitudes of 5 - 32° on either side of the equator[310. It is grown at elevations between 150 - 1,200 metres^[1]. It can succeed with an annual rainfall below 600 mm, but requires about 750 mm annual rainfall for a reasonable single harvest and at least 1500 mm if it is to be harvested more frequently^[1]. It prefers warm and sunny conditions with average daily temperatures of 20 - 25°c; temperatures of 25 - 30°c for extended periods can significantly reduce yields and suppress flowering^[1]. Frost causes damage at all growth stages and at higher elevations aboveground plant parts may die back during the cool season^[1]. Even slight frost at harvesting can be devastating and may reduce yields by half^[1]. In its natural habitat this species grows on poor, often slightly alkaline soils (pH 7.5 - 8.5) of sandy-loamy to loamy texture. Soils rich in organic matter and nitrogen are reported to yield high quality oil. It can also succeed on slightly saline soils^[1]. In cultivation, fertile well-drained soils of pH 6 - 7 are considered optimum. On alkaline soils (pH 8.5 or higher) growth and yields are reduced, but oil quality is not affected^[1]. Gingergrass does not tolerate acid soils but is fairly tolerant of prolonged periods of heavy rain that saturate the soil and also of imperfectly drained soils. Long days seem to favour oil production, both in quantity and in geraniol content^[1]. There are two forms of this species and these hybridize spontaneously in the wild wherever their habitats overlap. They are very similar to look at but differ considerably in the essential oil they produce:- Var sofia. Known as Gingergrass or Sofia. A tetraploid form, the essential oil has a turpentine-like aroma and a geraniol content of up to 65%^[1]. It grows in dense masses; its habitat is wetter and less sunny^[1]. Var martini. Known as Palmarosa or Motia. A diploid form, the essential oil has a floral rosy smell and a geraniol content of up to 95%^[1]. It grows in scattered patches; habitat dry and sunny^[1]. See the separate record for more information on this plant. It grows naturally in round clumps or tussocks, sometimes forming continuous closed stands of several hectares^[1]. It is strongly cross-pollinated and wild stands are highly variable. Oil yield and geraniol content are highest under long days^[1]. New plantations should be weeded several times, but an established crop quickly smothers most weeds after being harvested. Yields tend to decline rapidly if the plants are not fertilized regularly^[1]. Plants should be harvested when they are flowering, the oil content of the flowers is highest after opening and drops dramatically after flowering^[1]. The first harvest can be taken about 6 months after planting; the number of subsequent harvests per year depends on temperature and water availability with up to 4 harvests per year possible in some areas^[1]. The time of harvesting affects oil yield and quality. Harvesting during the rainy season gives high herbage and oil yields, but low geraniol content, while during the dry season herbage and oil yield are lower and geraniol content higher^[1]. The height of cutting is generally 20 cm above the ground. Cutting high leaves a substantial stubble, so reducing the cost of harvesting and distillation, but cutting low stimulates regrowth of the crop^[1]. Well managed plantations produce annual herbage yields of 10 - 15 t/ha, giving 50 - 100 kg oil. Improved cultivars may yield up to 25 t/ha of herbage producing 150 kg oil^[1].