I didn't have very much hope because stevia is very tropical, but I gave it a go, and now have two plants in pots. They were outside for the summer and looked pretty ragged and poorly. I brought them in to a windowsill a few weeks ago and they greened up, and this one especially grew a lot. I close the wool curtains every night and open them for the day. The window is a direct south-facing unobstructed window, so things get very hot. But, since my house is only solar heated, it will get chilly from the end of December to early February, like down to 10C (50F) at night, maybe sometimes lower. That's supposedly too chilly for stevia, so I'm not 100% confident it will survive and thrive. Anyway, I'm feeling pretty pleased with it right now.
I haven't used it more than tasting a bit of one leaf so far; I think I'll mostly only use it in tea and herbal tea, but let's see. I used stevia powder in lemon curd, replacing half the sugar, and it came out delicious, no problem at all. But stevia supposedly isn't good in actually cooked or baked things.
Works at a residential alternative high school in the Himalayas SECMOL.org . "Back home" is Cape Cod, E Coast USA.
I have a friend in Nova Scotia who grows stevia. Her favorite way to use it is to make a glycerite by chopping the leaves very finely, placing them in a jar and covering them with vegetable glycerin.
It doesn't matter much if the leaves are fresh or dried, as long as they're healthy. So you can do a quick harvest if the plant doesn't make it.
You can leave the jar to steep for several weeks or longer (shaking regularly) or you can steep it faster by warming the jar. I used to steep my lemon balm glycerite on the coolest corner of the wood stove for a week or in a sunny window. But you can also use a water bath, double boiler or slow cooker on low filled with water with a tea towel lining it, and steep the jar for a day or more.
I usually put my finished glycerite in a dropper bottle and if it's too strong, just dilute with some plain glycerin. I've bought stevia liquid drops at the store and they've worked great for baking, as long as I add them to the liquid ingredients and mix well.
Have fun with it!
I also use mine in tea and in smoothies or such, haven't tried it cooked.
I find that mine drops its leaves and dies back when it gets cold. I cut that back and it grows back in the spring. It sounds like my conditions are a bit cooler than in your house (9B here, we rarely get below zero), but you might get lucky with the plant inside.
I am somewhat disappointed that I don't use it as much as I hoped I would. I was super thrilled to find it, but in the end mostly I just give cuttings to people.
I grow stevia here. I bring it in for the winter too. I keep it in our sun room and it has no heat other than a freezer running. It gets down into the low 50s at night and I never seem to have an issue. My oldest plant is 5 years old that was from seed. I have a bunch that I started from cuttings doing well right now.
I noticed here if it is direct sunlight in the summer it gets to hot and wilts. I started putting them where they only get morning sunlight and they do great.
I cut it 3 times a summer almost all the way down. I strip the leaves and dry them on racks. They stay nice and green. I sell 1/2 pint bags full of leaves at my sons food stand for 2 bucks. I don't have much left over for us this year.
The best place to pray for a good crop is at the end of a hoe!