Stevia rebaudiana is a plant that contains sweet glycosides. The plant is native to Brazil and Paraguay in South America and is used as an artificial sweetener because it is sweeter than cane sugar. Stevia has adapted to growing in zones with mild winters, making it available to certain areas throughout the United States.
The plant is from the genus Stevia and only the rebaudiana species is known for the sweet taste. Stevioside is the extract found in the plant that is the primary cause of the sweet taste. The highest levels of stevioside is found in the leaves. Stevia plants reach up to 2 feet in height and grow in USDA Zones 8 or higher. Stevia is classified as a tender perennial and will winter through under mild conditions.
Plant stevia is the spring once the soil temperature has reached at least 65 degrees Fahrenheit. The stevia plant prefers a soil that is sandy loam and high in organic matter. The native soils in South America are high in acid, however, stevia will grow well in a neutral pH level. Raised growing beds provide a good environment as the plant requires moist, but not water logged, soil. Too much water will cause the roots and stems to rot. Plant stevia in sunny areas where there is afternoon shade. The plant prefers longer day lengths rather than an intense sun situation.
Care and Maintenance
Stevia plants should be watered at least once a week unless there are adequate rainfall amounts. An application of garden fertilizer should be applied in spring. Do not use a high nitrogen fertilizer on the stevia plants. Adding boron to the plants will assist with the plant maintaining a high sweetness level. Mulch is not required, but will help maintain a moist soil level. The plants will produce the best crop in year two. By years 3 or 4, the productivity of the plant decreases and should be replaced with new cuttings.
During harvesting, cuttings can be taken to start new plant growth for the next season. The cutting must be at least 2 to 4 inches in length with 2 leaf buds planted above the soil level. To plant, first dip the cut end of the plant in a rooting base that can be purchased at gardening retail stores. Place the cut end in a rooting medium for 2 or 3 weeks, until new root growth has started. Once roots have formed, transfer the cutting to 4 ½ inch pots.
Harvest the stevia leaves late in the fall. This allows the cool autumn weather to assist with releasing additional sweetness into the leaves. Harvest should occur prior to the fall frost or cover plants when there is a risk of early frost. To harvest, cut the stems and remove the leaves from the plant as they contain the highest level of sweetness. Leave at least 1/3 of the stem on the plant if the plant will be left for re-growth the next season. Dry stevia leaves prior to using them by placing them on a screen in full sun for 12 hours or using an in home dehydrator.