Stevia cultivation requires 1.400 to 1.800 mm of rain per year. The plant does not support prolonged droughts. It requires high brightness. A temperature above 20 ° C is required, making it ideal between 24 and 34 ° C. It resists and thrives to 43 ° C if accompanied by frequent rainfall.
Temperatures between 5° and 17° C do not kill the plant but inhibit or stop their leaf development; temperatures below 5° C (frost) kill the plant. The plant thrives from 0 m.a.s.l. up to 1,200 m.a.s.l.
Stevia grows and develops well in sandy loam or clay loam soils with pH between 5.5 and 6.5. In areas with high rainfall, it is recommended that the ground have a slight slope to prevent waterlogging; it is also advisable to establish contours. Saline soils are not recommendable.
The plant is not very demanding in macro and micronutrients. However, if the soil is clay or sandy, it is recommended to add organic matter. Planting should have black soil or organic matter. With these products, the necessary amendments will be carried out in order to avoid possible use of synthetic fertilizers. If the soil has marked acidity, agricultural lime will be applied to reduce the acidity. We do not recommend poultry manure because it facilitates the presence of nematodes.
To date in Colombia, significant pest or disease attacks have not been reported. There have been sporadic attacks by fungi: Oidium, Alternaria and Septoria sp steviae, which with regular preventive spraying and timely reaction could have been totally controlled. Frequent monitoring of the plantation to detect and immediately remove suspicious plants (burn and bury) is important. Outside of Colombia, fungal diseases and nematodes have been detected mainly in large commercial plantations in Paraguay and Brazil, where the insects that attack Stevia are reported, as in the case of aphids, cutworms, ants, slugs and beetles. Among the diseases caused by fungi, Alternaria steviae, Septoria sp and Sclerotium sp attacks are mentioned as the most abundant. Also Rhizoctonia solani, Sclerotinium rolfsii, Botrytis cinerea, Fusarium sp and Cercospora steviae. Among nematodes, it is the Meloydogyne sp.
It takes place in plants that already have flower bud, as it is at this time that the plant has reached its highest levels of sweetening power. This work must be executed with sharp and previously disinfected scissors. The cut is made at a height of 7 to 10 cm of soil. The harvested product is accommodated in baskets or plastic tarps, and then carried to the dehydration zone.
Cutting or cultivation of leaf will cycle between 45-60 days depending among other factors such as climate, soil conditions and fertilization, and thus from 6-8 crops can be achieved per year, making it possible to reach a production of 9-12 tons of dehydrated leaf per hectare per year. In countries like Paraguay and Brazil 3 or 4 cuts are made per hectare per year.
Fresh branches freshly harvested should be collected in plastic baskets, without pressing or stirring them. Depending on temperature and humidity, branches dry out on average between 1-2 days.
The use of ovens is recommended for dehydration. Through these ovens, a better quality of dehydrated leaf is achieved in a much shorter time and with better sanitary conditions. The temperature must be constantly monitored and controlled by an electronic device, it must not exceed 80° C. After dehydrating, branches are shaken, thereby detaching the leaves from the stems. A disadvantage of this system is that of a higher cost for the dehydration process, however, the advantages far outweigh this item.