Nicole shared this information from a presentation she gave.
Stevia leaves are sweetest and most flavorful before the plant starts to bloom. And the leaves are also at their sweetest during the cooler temps of fall. Cut whole stems of the plant but never more than 1/3 at a time.
Drying:
Hang the stems or leaves in bunches upside down in a warm dry place with good air circulation. Attics can work well. Or spread the leaves on a non metal screen outdoors on a dry sunny day. If it is breezy, cover with another screen to avoid them blowing away. Or use a food dehydrator. An oven turned to 140 will also work.
Storing:
Once the leaves are dry, separate them from the stems and grind them into a powder. Store in an airtight container. Small glass jars work well for storing herbs as they are truly airtight.
Sandy