I bought 2 stevia plants last spring. I planted one in the ground and potted the other one in a 10" clay pot. I took cuttings from both in early fall, and brought the potted one in to overwinter.
The potted plant did well in my SE kitchen window supplemented by a clamp-on utility light with daylight CFLb. Late winter the sweet pepper plant next to it became infested with aphids, but the stevia did OK for a while... until early spring when the ants invaded and decided stevia made a good pasture for the aphids.
It became rather spindly despite the supplemental light and I cut it back by 1/3 when I set it out in spring when I planted out the tomatoes, but by that time, it was sending out new shoots both from the stems as well as from the base of the plant -- I pruned to just above the new shoots and pruned off spindly side shoots and branches. I think I didn't repot but just added a layer of compost, but I'm not positive on that. There WERE two earthworms in the container the entire winter and they were still in the pot when I put it outside.
The cuttings were grown in 4" square plastic pots upstairs where it's about 5 degrees warmer, also in SE windows, one with supplemented light (actually it got the prime spot directly under the light bulb). The one with supplemented light grew well, even though it was infested by red spider mites and aphids by early spring. A few cuttings succumbed to the bugs, but enough -- 2 or 3 survived (I had 5 cuttings in each pot originally). The cuttings without supplemented light died off (which is unfortunate because I put the cuttings from each plant in each pot -- of course I didn't label them properly, so I don't know which plant survived and which didn't).
Anyway, this spring, I planted out the surviving cuttings in the front of the tomato bed. The potted plant I placed in somewhat more shaded location by the path behind one group of tomatoes. They are both doing well. I just trimmed the cutting grown plants by 1/3 (They were about 20" tall). I believe this is the time to harvest since we're experiencing cooler 60's nights -- heading for upper 50's tonight -- and I'll be taking several more harvests from all three? plants. (Actually if I had a longer season, they could be harvested again for 2nd cutting)
They tell you to keep pinching the flower buds and not let them get in "flowering mode" because the leaves will become bitter. I think the dried ground up leaves "leaves" a slight aftertaste on the tongue -- and I noticed the floating ground stevia effect too
Interesting to nibble on sweet bits with each swallow, but not really the ideal
I've run dried leaves/stems in the coffee grinder along with the coffee beans. That adds a mild sweetness. I also add the dried leaves to herbal tea mixes. I also stir my hot coffee and tea with fresh stiffer stems, leaves attached.
I gave a leaf to the kids and told them to try nibbling it. DD8 LOVED it and ran to tell her sister.
DD11 is a bit more cautious and hadn't tried it yet, but she decided it was great and tried making tea with it, adding warm water since she said she can't tolerate hot.
I think all three of us will be continuing to experiment. I want to try making tinctures -- maybe with brandy for adding to tea and ... what? whiskey? for adding to coffee?
Maybe hot water decoctions? I need to research some more....