Common Name: Stevia

General Information

Stevia rebaudiana is a slender, erect, perennial plant growing around 1 metre tall. The plant has a vigorous rhizome and shallow root system[].
The plant is often cultivated in tropical and subtropical areas for its sweet-flavoured edible leaves from which a sweetener can be extracted[]. The plant also has medicinal uses and is an ingredient of commercial cosmetic preparations.

Known Hazards

None known

Botanical References

Range

S. America - southern Brazil, Paraguay.

Habitat

The edges of marshes and grassland communities at elevations up to 700 metres[]. Infertile, sandy acid soils with shallow water tables.

Properties

Edibility Rating
Medicinal Rating
Other Uses Rating
Habit	Perennial
Height	1.00 m
Pollinators	Insects
Cultivation Status	Cultivated, Wild

Cultivation Details

A plant of the subtropics and tropics, where it can be cultivated at elevations from sea level up to 1,500 metres. It can also be grown in more or less frost-free regions of the temperate zone. It grows best in areas where annual daytime temperatures are within the range 18 - 30°c, but can tolerate 15 - 43°c[]. When dormant, the plant can survive temperatures down to about -6°c, but young growth can be severely damaged at 0°c[]. It prefers a mean annual rainfall in the range 1,000 - 1,400mm, but tolerates 500 - 1,800mm[].
Prefers a sandy soil, requiring a warm sunny position[]. Prefers a pH in the range 5 - 6.5, tolerating 4 - 7.5[].
A first harvest can take place 2 months after planting, which is about 6 months after sowing the seed[]. Further harvests can be taken at monthly intervals and can continue for about 5 years before the plants will need to be replaced[].
Flowering occurs 40 - 60 days after sowing or cutting. Long days, however, promote more leaf production resulting in a higher content of stevioside, on dry-matter basis[].
In Japan, the yield in the first year is 400 - 500 kilos per hectare of the dried leaves, while yields in the following years vary between 1.5 - 2 tonnes of dry leaves. In western Java a yearly production of 3 tonnes of dry leaves is possible[].

Edible Uses

Leaves - raw or cooked. A very sweet liquorice-like flavour[]. The leaves contain 'stevioside', a substance that is 300 times sweeter than sucrose[]. Other reports say that they contain 'estevin' a substance that, weight for weight, is 150 times sweeter than sugar[, , , ]. The dried leaves can be ground and used as a sweetener or soaked in water and the liquid used in making preserves[]. The powdered leaves are also added to herb teas[]. The leaves are sometimes chewed by those wishing to reduce their sugar intake[]. The leaves can also be cooked and eaten as a vegetable[, ].

Medicinal

The leaves are said to be used as a herbal remedy for diabetes[]. Stevia is not a remedy for diabetes, but can be used as a sugar-free sweetener, and is reported to have some effect upon regulating glucose levels[, ].
The plant has also been used in the treatment of candidiasis, skin abrasions, dental caries, depression, hypertension, obesity, wound healing and as tonic and sweetener[].

There have been various studies into the activities of stevia:-
Lupeol 3-palmitate, found in the leaf, has shown marked inhibition of inflammatory activity[].
The administration of a crude extract of Stevia dried leaves for 40 to 60 days induced systemic and renal vasodilation causing a lowering of blood pressure, increased urine flow and the increased excretion of sodium in the urine[].
Stevioside, the main sweetening agent in the leaves, has been shown to cause vasorelaxation through an inhibition of calcium influx into the blood vessels. A study using 250mg stevioside capsules three times daily found stevioside to be a safe and effective compound or supplementary therapy for hypertension[].
A study of the ethanolic and ethly acetate extracts of the leaves have indicated that they may be useful as a potential source of natural antioxidants[].
Stevioside has been shown to lower blood glucose. It dose-dependently decreases the protein levels of phosphoenol pyruvate carboxykinase, reducing insulin resistance. The study concludes that stevioside can regulate blood glucose by enhancing insulin secretion and insulin utilization where there is insulin-deficiency[].
The dried and powdered leaves have shown significant hypoglycaemic effects and body weight reducing effects[].
Four solvent extracts of the leaves have shown effective antibacterial potential. The acetone extract showed no toxicity to normal cells and showed both anti-proliferative and anticancer activities. The study confirms the antimicrobial and antitumor activities of the leaf extracts, suggesting a potential drug that warrants further studies and development[].
A study on the effects of aqueous extracts of the leaves on glucose tolerace in normal volunteers showed an increase in glucose tolerance, with a significant decrease of plasma glucose during the test and after overnight fasting in all volunteers[].

Other Uses

An extract of the leaves is used as an ingredient in commercial cosmetic preparations as a skin conditioner[].

Propagation

Seed - sow spring in a warm greenhouse and only just cover the seed. Make sure the compost does not dry out. Prick out the seedlings into individual pots and grow them on fast, planting them out after the last expected frosts. It could be worthwhile giving them some protection such as a cloche or cold frame for a few weeks after planting them out until they are growing away well.