How do I know when to obtain the leaves from my stevia plants? I live on the border of USDA zone 7 and 8.? ...

So we've mowed the sward and rake up...
Answers:    I have never harvest the leaves, just grown the plant. I would assume you can newly pick off the leaves as needed and tolerate the plant continue on.

If you google the botanical given name, Stevia rebaudiana, you will get greatly of links about the plant. I can't find a correlation on just using and harvest the leaves, it mostly talks just about commercial uses and availablilty. Here are two links with rather info:

http://www.stevia.com/SteviaArticle.asp?...

http://www.rain-tree.com/stevia.htm

Maybe you will have better luck finding something. Good luck.
How normally and for how long a year...
SETIVA??? ZONES??? WTF?