Stevia is a sub-tropical to tropical plant who's leaves are much sweeter than sugar. . Different plants have different levels of sweetness and there are even differences on the same plant from cutting to cutting so using home grown stevia can be a bit of a challenge, but the rewards are well worth it.
Studies done on this plant suggest that the compounds in the whole leaf have anti-hyperglycemic, anti-hypertensive, anti-inflammatory, anti-tumor, anti-diarrheal, diuretic, and immunomodulatory actions. Most stevia found in stores contains only the stevioside compound that gives the leaf it's sweet taste. The other compounds in the leaf are those that do these jobs. What's really interesting about this plant is that it only seems to affect blood sugar, blood pressure, etc. when levels are abnormal. Sweet! According to the info out there, there are no known harmful side-effects like artificial sugar substitutes, however, I do know a couple of people who say it gives them headaches.
You can grow stevia from seed, but only "black" seeds will germinate. I did have a plant that flowered and put out seeds a couple of years ago that produced babies, but from what I've read, plants from seed may or may not have the sweetness of the parent plant. Propagating from cuttings is the preferred method, but I haven't been successful at that :(
To use the stevia, I dry the plants and put them in the freezer. When I want to use some, I grind the leaves in a coffee grinder and sweeten with the powder to taste. Stevia doesn't ferment, so it's no good for things like wine or vinegar and when making jams or jellies you really need a no-sugar pectin because it doesn't contribute to the jelling process like sugar does.
The plants are sometimes hard to come by. Last year I didn't find any until August and they weren't as sweet as other plants I've had, but I dug them up and brought them inside because I didn't want to be without this year.
They look kinda scraggly by spring, but once I get them back outside in the sun they will perk up. I've done this before, but I lost them last winter because I had to be gone and they didn't get watered enough. I'll wait until the temps stay above 50 most of the time before I put them back in the garden. I've killed a few by putting them out to soon. They love a thick mulch on well drained loamy soil. Raised beds are perfect for them. Once established, they tolerate temps in the 33-50 degree range quite well. I've even covered them like tomatoes when there was a light frost and had them come through fine.
Unless I can get enough quality plants, I won't be bringing stevia to the markets. So far, I've only been able to produce enough for my breads and jams, but it's really nice to be able to brag that I grow my own!
God Bless You All!