Stevia is an incredibly sweet herb, obtained by a natural selective breeding process of the sweetest Stevia parent plants. The sweetener, stevioside, extracted from the plants, is 300 times sweeter than sugar. The fresh leaves have a nice liquorice taste. What makes the Stevia plant so special is that it can be used to replace sugar (sucrose). Many different uses of Stevia are already well-known: as table sugar, in soft drinks, pastry, pickles, tobacco products, candy, jam, yoghurt, chewing gum, sorbets... The dried leaves of Stevia are about 40 times sweeter than the sugar.
The documented properties of Stevia are antibacterial, anti fungal, anti-inflammatory, anti-microbial, anti-viral, anti-yeast, cardiotonic, diuretic, hypoglycemic and hence a boon to diabetic people, hypotensive, tonic, and vasodilator. Indeed, the leaves contain diterpene glucosides with a sweet taste but which are not metabolised and contain no calories. The biggest part of the sweet glucosides consists of the stevioside molecule.
Stevia rebaudiana Bertoni (Bertoni) is a perennial herbaceous plant and is part of the Asteraceae family. This family includes well-known plants such as dandelion, sunflower and chicory. The history of the culture of Stevia mainly stems from Paraguay and Brazil. Originally Stevia only grew in the northern regions of South America but its cultivation has become popular worldwide. . The plant has been known for centuries by the native Guaranay-Indians for the sweet taste of its leaves. They use it, amongst other things, to make "mate" herbal tea. Stevia is often referred to as the sweetest plant of the world.
Its leaves are about 5 cm long and 2 cm wide and are planted crosswise, facing each other. In the wild, the height of the plant varies from 40 to 80 cm but when cultivated, the Stevia can grow upto 1 metre high. Stevia can be grown on relatively poor soil. The plants can be used for commercial production for 6 years, during which five times a year a harvest takes place of the part of the plant that is above the ground. The roots remain in place and so the plant regenerates again. Plants, which are 1 metre high, have a dry weight of 70 g on average. The dry weight of the leaves can vary from 15 to 35 g per plant.
The principal advantages of Stevia are the following:
It is a completely natural non-synthetic product.
It has got ZERO Sugar. Stevioside (the sweetener) contains absolutely no calories.
The leaves can be used in their natural state.
Thanks to its enormous sweetening power, only small quantities need to be used.
The plant is non-toxic.
The leaves as well as the pure stevioside extract can be cooked.
No aftertaste or bitterness.
Stable when heated up to 200 degrees.
Non fermentative.
Flavour enhancing.
Clinically tested and frequently used by humans without negative effect.
Ideal, non-addictive sweetener for children.
Cultivation Process of Stevia
Land Preparation
The land sites are plowed and or cultivated twice to prepare a fairly smooth, firm-planting surface.
Transplants
Transplants from cuttings would be superior, however cost makes it prohibitive. Stevia must be propagated from seed in plug trays placed in a greenhouse for a period of 7 – 8 weeks.
Planting
Depending on different climatic conditions Stevia is cultivable throughout the year except for times when it is extremely hot or cold. Stevia plug plants are planted into the field on either 53 cm or 61 cm row spacing with a total plant density in the order of 30,000 plants per acre.
Fertilization
The plant appears to have low nutrient requirements; however a soil test should be conducted. We are committed and encourage total organic cultivation.
Irrigation
Normally, the Stevia plant requires frequent, shallow irrigation. Generally, one applies irrigation if the stem tips are drooping at least one time per week.
Weed Control
This crop also requires hand hoeing and weeding.
Pests
Insect pest pressures other than cutworm are minimal. Septoria disease can cause considerable damage to the Stevia crop. Animals seem to like the sweet taste of stevia, too.
Harvesting
Time of harvesting depends on land variety and growing season. Generally it can be scheduled when plants are 40-60 centimeters in height. Shorter days induce flowering. Optimum yield (biomass) and stevioside quality and quantity is best just prior to flowering. The plant will tolerate very low temperatures.
Drying
Drying of the woody stems plus the soft green leaf material is completed immediately after harvesting utilizing a drying wagon or a kiln. Depending on weather conditions and density of loading, it generally takes 24 to 48 hours to dry Stevia at 40°C to 50°C. An estimated 21,500 kg/ha of green weight is dried down to 7000 kgs. of dry herbage per hectare.
Threshing
immediately following drying, a specially designed thresher/separator is necessary to separate dry Stevia leaves from its stem. Stem and leaf portions tend to be equally represented at 3000 kgs / ha each.
Growing Stevia
You need not be a South American planter to be a successful stevia grower. While the herb's native locale may make it appear somewhat exotic, it has proved to be quite adaptable and capable of being cultivated in climate zones as diverse as Florida and southern Canada.
True, home-grown stevia may lack the potency of refined white stevia extract; whole stevioside content generally ranges from 81 to 91 percent, as compared to a leaf level of approximately 12 percent. But it can provide you with a quantity of freshly harvested stevia 'tea leaves' to augment your supply of commercial stevia sweeteners.
Organic gardeners in particular should find stevia an ideal addition to their yield. Though nontoxic, stevia plants have been found to have insect-repelling tendencies. Their very sweetness, in fact, may be a kind of natural defense mechanism against aphids and other bugs that find it not to their taste. Perhaps that's why crop-devouring grasshoppers have been reported to bypass stevia under cultivation.
Then, too, raising stevia yourself, whether in your back yard or on your balcony is another positive way you can personally (and quite legally) protest the wrongheaded government policies that have for so long deprived the American people of its benefits. A kind of contemporary Victory garden.
How to start your own Stevia patch
It would be difficult, at best, to start a stevia patch from scratch -- that is, by planting seeds. Even if you could get them to germinate, results might well prove disappointing, since stevioside levels can vary greatly in plants grown from seed.
The recommended method is rather to buy garden-ready 'starter' plants, which given stevia's 'growing' popularity, may well be obtainable from a nursery or herbalist in your area -- provided you're willing to scout around a bit. If you're not, or are unsuccessful in locating any, there are at least three growers of high-quality stevia who will ship you as many baby plants as you'd like.
Keep in mind that not all stevia plants are created equal in terms of stevioside content, and, hence, sweetness. It's therefore a good idea to try to determine if the plants you're buying have been grown from cuttings whose source was high in stevioside.
Because tender young stevia plants are especially sensitive to low temperatures, it's important that you wait until the danger of frost is past and soil temperatures are well into the 50s and 60s before transplanting them into your garden.
Once you begin, it's best to plant your stevia in rows 20 to 24 inches apart, leaving about 18 inches between plants. Your plants should grow to a height of about 30 inches and a width of 18 to 24 inches.Â
The care and feeding of Stevia
Stevia plants do best in a rich, loamy soil -- the same kind in which common garden-variety plants thrive. Since the feeder roots tend to be quite near the surface, it is a good idea to add compost for extra nutrients if the soil in your area is sandy.
Besides being sensitive to cold during their developmental stage, the roots can also be adversely affected by excessive levels of moisture. So take care not to over water them and to make sure the soil in which they are planted drains easily and isn't soggy or subject to flooding or puddling.
Frequent light watering is recommended during the summer months. Adding a layer of compost or your favorite mulch around each stevia plant will help keep the shallow feeder roots from drying out.
Stevia plants respond well to fertilizers with lower nitrogen content than the fertilizer's phosphoric acid or potash content. Most organic fertilizers would work well, since they release nitrogen slowly.
Gathering Autumn Stevia Leaves
Harvesting should be done as late as possible, since cool autumn temperatures and shorter days tend to intensify the sweetness of the plants as they evolve into a reproductive state. While exposure to frost is still to be avoided, covering the plants during an early frost can give you the benefit of another few weeks' growth and more sweetness.
When the time does come to harvest your stevia, the easiest technique is to cut the branches off with pruning shears before stripping the leaves. As an extra bonus, you might also want to clip off the very tips of the stems and add them to your harvest, as they are apt to contain as much stevioside as do the leaves.
If you live in a relatively frost-free climate, your plants may well be able to survive the winter outside, provided you do not cut the branches too short (leaving about 4 inches of stem at the base during pruning). In that case, your most successful harvest will probably come in the second year. Three-year-old plants will not be as productive and, ideally, should be replaced with new cuttings.
In harsher climates, however, it might be a good idea to take cuttings that will form the basis for the next year's crop. Cuttings need to be rooted before planting, using either commercial rooting hormones or a natural base made from willow tree tips, pulverized onto slurry in your blender. After dipping the cuttings in such a preparation, they should be planted in a rooting medium for two to three weeks, giving the new root system a chance to form.  They should then be potted -- preferably in 4.5-inch pots -- and placed in the sunniest and least drafty part of your home until the following spring.
Unlocking the Sweetness in your Harvest
Once all your leaves have been harvested you will need to dry them. This can be accomplished on a screen or net. (For a larger application, an alfalfa or grain drier can be used, but about the only way an average gardener might gain access to such a device is to borrow it from a friendly neighborhood farmer). The drying process is not one that requires excessive heat; more important is good air circulation. On a moderately warm fall day, your stevia crop can be quick dried in the full sun in about 12 hours. (Drying times longer than that will lower the stevioside content of the final product.) A home dehydrator can also be used, although sun drying is the preferred method.
Crushing the dried leaves is the final step in releasing stevia's sweetening power. This can be done either by hand or, for greater effect, in a coffee grinder or in a special blender for herbs. You can also make your own liquid stevia extract by adding a cup of warm water to 1/4 cup of fresh, finely-crushed stevia leaves. This mixture should set for 24 hours and then be refrigerated.
