Collect used and washed food containers, such as sour cream, cottage cheese or yogurt cups. Poke small holes in the bottom of the containers with a thin nail. You may also use a commercial seeding tray, found at garden centers and nurseries.
Fill your containers with a commercial potting soil--free of disease, fungus and stray seeds--to within ½ inch of the tops of the containers.
Spray water onto the soil, then mix the soil until it is completely moist but not sopping wet.
Drop two stevia seeds in each container, separated a bit. Use just a dash of potting soil to cover them. The seeds are very small and do not need a heavy covering of soil.
Place the containers in a tray. If you have chosen to use a commercial seeding tray, a lower water reservoir should be included. Pour about a cup of water into the bottom of the tray. Cover the tray with a sheet of clear kitchen plastic wrap. Do not seal it around the sides of the tray, as the seeds need some airflow.
Place the tray near a sunny window in a warm room that is between 60 and 75 degrees Fahrenheit. If your room is not warm enough, you may use a heating mat beneath the tray. These can be found in nurseries or garden centers.
Check the soil in about 4 or 5 days. When the tray is dry, add another cup of water and lightly spray the soil. Continue watering in this manner to keep the soil moist but not too wet.
Remove the plastic wrap from the tray as soon as the stevia seeds begin to germinate (when green sprouts appear out of the soil). This will take between 6 and 12 days.
Cut the weakest plant, at soil level, in each container at about two weeks from the seeding date. You want only one healthy, strong plant for each pot.
Harden off the stevia seedlings before transplanting them outdoors. Place them outside a few hours, increasing the amount every day until they have been out a full 24 hours. The temperatures should not dip below 40 degrees Fahrenheit.
Transplant the stevia seedlings outdoors or into larger, 4- to 6-inch outdoor pots eight to 10 weeks after seeding.