We find that Stevia will grow in almost any climate, if it is given the correct soil, fertilizer, and light conditions. Full sun is preferred but in hot weather the leaves will be smaller. It is adaptable to most areas of the country but does best where the night temperatures stay above 65F. Stevia is not frost hardy and must be planted each year. In areas where there is no frost, Stevia is still replanted each year, due to the poor growth of the 2nd year root system.
Stevia should be planted in the spring after the soil temperature reaches 65 deg F., in full sun and in a light, sandy, open, well drained soil with neutral pH. In southern states, stevia could use some filtered afternoon shading. Use a standard garden fertilized. Do not use a lawn fertilizer or fertilizers with high nitrogen. Adding extra Boron will help keep the glycosides level high. Soil could be “mounded up” into a “raised bed or hill,” this would provide good drainage. Apply a layer of mulch, such as wood chips, or bark mulch. This will help keep roots cool, preserve water, keep the leaves clean from soil (prevents dirty taste in green powder) and holds down the weeds. Avoid weeding around mature stevia plants as their brittle branches are easily broken. Avoid overwatering after transplanting and in winter as a houseplant.
Keep evenly moist during summer heat. Drip or soaker hoses are very effective for summer watering. Stevia grows best in summer weather. Plant outside early spring in vegetable garden after danger of frost. Methods which allow a gardener to plant earlier, such as tunnels, hot caps, and such, are very beneficial. Pinch tips out about every 3 weeks for first 1-2 months. This will encourage side branching which will create a bushier plant, that is not spindly. We save and dry all the tips we pinch to sweeten our summer teas with. Harvest entire plant just before flower buds open. Harvest early in the morning and dry in full sun for highest glycoside /sugar content, whether pinching tips or entire plants. The full harvest will occur in late September or early October. Because it is a member of the “Aster” family, once flowering has begun, not a single normal leaf will be produced. Removing flower heads is not effective. Failure to harvest plants before several flowers have opened, will allow the glycoside /sugar content in the leaves to decline, this will impart a bitter/dirty flavor to the leaves. Harvesting is done by cutting the entire plant at the base. In order to keep the glycoside /sugar content high Stevia must be dried quickly in full sun. Avoid using food dehydrators or open oven doors as this will also tend to cause a bitter flavor. “Rake” fingers through branches to remove crisp-dry leaves. Remove any small branches and grind leaves into powder using an electric coffee grinder for 25-30 seconds. Food processors are not as effective because of their slow RPMs. Store green powder in “Mason” jars, “Zip-lock” baggies etc. Dried green stevia powder will last indefinitely or at least until the next harvest.
Stevia rebaudiana seed is available, but difficult to find for several reasons:
- Seed is normally very low germination. However from our work with a research university, we have discovered that if you select the very dark seeds and plant only them your germination should exceed 85%.
- Stevia grown from seed may or may not be sweet. Usually only universities grow Stevia from seed – looking for that one in a million plants that have more Stevioside than the plants we sell.
Once you find Stevia plants with high levels of Stevioside, it is best to propagate them from cuttings or tissue culture. Herbal Advantage, Inc. is currently working with farmers in the USA, Europe, and Russia to produce Stevia on large scale farms.
The leaves contain about 12% Stevioside (one of the sweet factors). The old brown Stevia leaves will contain 8 to 10% Stevioside. The stems contain about 3% Stevioside. The leaves should be harvested early in the morning and dried in the full sun. Break the leaf with your hands or put them a blender to make powder. We have 2 Stevia cook books in stock.