Stevia

Stevia rebaudiana

Stevia has only recently gained attention and become available in health food stores in the U.S. as a natural non-sugar sweetener.  It is a tropical plant, native to Paraguay and Brazil, but it does very well in Kansas, and probably in other Great Plains states.  An herb company in Missouri has recently begun a breeding a selection program to improve Stevia germplasm, and select for even sweeter plants.  Stevia was originally used in eastern Parguay to sweeten the local tea, Yerba Mate, but also used the plant medicinally.

Family:  Compositae
Life cycle: annual; herbaceous
Native:  Paraguay/Brazil
Height: 12-15”
Sun: full sun, partial shade, shade?
Soil:  will respond well to rich, high organic matter soil.
Water:  Prefers an environment that is hot and humid, but did well in our field trials in hot, windy Kansas.  Will tolerate drought, but if possible, supply moderate to high rates of irrigation.
Flowers:  flowers are delicate and white, and bloom on and off throughout the growing season.  Flowers are more abundant in the fall.
Propagation:  plant is easily propagated from cuttings, especially if taken before the plant blooms.  Seed propagation is also possible.  Keep seeds moist and warm, and expect about 30% germination over a 2-3 week period.  This plant can be grown outdoors year-round in tropical regions, and in Kansas could be brought inside as a house plant for the winter.  One could also collect cuttings in the fall for rooting and spring re-planting.  Will not be winter hardy in Kansas outdoors.
Pests:   No significant insect or disease pests noted in our plots.  Rabbit and deer feeding also does not appear to be a problem.  However, in one set of test plots, 4 of 5 plants disappeared between
field day and harvest, without a trace, and our primary suspects are two-legged plant eaters.
Harvesting:   Clip leaves, or above ground portion any time during the growing season.  One source recommends fall harvest for the sweetest plants.
Parts used:  Leaves.
Used as:  The leaves of the plant are powdered and used as a
non-sugar based sweetener.  In some cases, an extract of Stevia is sold as a concentrated white powder to sprinkle on food.
Medicinal Benefits:  This plant has been used in folk medicine to treat hypertension, diabetes, and as a contraceptive.  However, it is currently popular in the market as a sugar substitute, and the glycosidal diterpens present in the leaves are 30 times sweeter than sugar, and the concentrated extract is 300 times sweeter.  One recipe conversion chart suggests that 3/8 tsp of Stevia is equivalent to 1 Tbl. of sugar, and that 2 Tbl of Stevia could substitute for 1 cup of sugar.
Market Potential:  Moderate to high.  Prices range from $6.50 - $36.77 per lb dw for the herb.

KSU Field Trial Data - 2000-2002.  

Summary of field trial data:   This species did well under Kansas conditions, especially considering its tropical origins.  It appeared healthy and vigorous, even in the hot wind, but of the two sites tested, the Hays site (non-irrigated, central/western KS) yielded about half (32 g/plant) the dry weight as the Wichita site, which was irrigated (72 g/plant).  This trial took place during the 2001 growing season, and another trial this year (2003) seems to be showing similar results, with larger plants in Wichita, under irrigated conditions, as compared to Olathe, which was not irrigated.  The vigor rating is 4.2 on a 1-5 scale, and no significant insect or disease pests were noted.  Since this is an above-ground herb, harvesting could potentially be mechanized, as long as quality control was maintained.  The price spread is a bit disconcerting, and with the high-end price more than 5 times the low end price, one wonders how to get that high price in order to make money with this crop.