Stevia is an herb that produces a no-calorie sugar substitute. Its extract can be up to 30 times sweeter than sugar. Stevia extract, when consumed, goes straight through the digestive system without breaking down and is therefore suitable for people with diabetes or who need to control their blood sugar levels. To plant stevia from seeds, start indoors in the late winter and transplant them outdoors after the last frost, or plant them outdoors after the last frost.
Visit an online nursery or herb store that sells seeds. Local nurseries may also sell stevia seeds, but are more likely to sell established plants or cuttings, if they sell stevia at all.
Choose a seed germination rate. You may have to visit several online stores in order to find the germination rate you desire. The higher the germination rate, the more seeds will sprout. For example, if the seeds have a germination rate of 80 percent, you can expect 8 out of 10 seeds to actually sprout (germinate).
Calculate how many seeds you need. Each plant of stevia can yield up to one-half pound of dried leaves, which is crushed and mixed with water to make stevia extract. Depending on the sweetness of your plant (which varies from seed to seed), one-half pound of finely crushed stevia leaves can produce the same sweetness as up to 150 cups of sugar. Therefore, if you decide you need 10 pounds of dried leaves, you will need to grow 20 plants. If the stevia seeds you purchase are labeled at 80 percent germination, buy and plant about 25 seeds to meet this goal. Buying a few extra seeds, especially if it's your first time growing stevia from seeds, is advisable.
Select the seeds that you want to buy and purchase them. Stevia seeds are usually sold by weight with an approximate seed count. Small packages, such as 10 mg packages that contain about 25 seeds, are ideal for the average home gardener who wants to grow stevia plants.