Stevia Seeding

I am curious to know the recommended amount of seed for stevia

planting. How long a row will a packet plant?
Stevia seed has a low germination rate of only 10-15%, probably because the plants are self infertile. Commercially they are usually reproduced by cuttings of superior plants and thus the plants are really just parts of the same plant and set no fertile seed. Packets contain enough seed to give you about a dozen plants. Space the resulting plants about 20-30cm apart.

Or by weight? How would one figure it?

One gram of Stevia seed contains about 2500 to 3000 seeds, As mentioned above, the germination rate is 10-15 %, so one gram would give you 250-300 plants under ideal conditions. Ideal conditions are deep rich sandy soil, a germination temperature of 20-25 degrees Celsius and exposure of the lightly buried seed in flats to light may help the germination.