Stevia is an ever popular herb to grow in the home garden. It can be used as a sweetener in baking, and in tea, and there is a commercial market for it. You will not be able to process it into the white powder sold in stores, but it is an interesting and challenging plant to grow. It has been grown and used for years in Central and South America, but will grow as far north as Southern Canada.
Stevia Soil Requirements
Stevia is best suited to growth in loam to sandy loam conditions but can also be grown in a clay loam soil if placed in a raised bed. Drainage for this plant needs to be exceptional. The plant prefers slightly acidic soil, but can grow in a range of pH levels. Soil should be about 60 degrees before planting, and should be dug to a level of about six inches.
Incorporation of compost into the soil is advised, especially with clay soil. The compost will help to break up some of the soil, and to provide good drainage. Stevia should never be grown in conditions where standing water is possible. The soil should have good nitrogen content although too much nitrogen can affect the flavor of the stevia negatively. Use blood meal or cottonseed meal to introduce nitrogen slowly to the soil. If you are in doubt, take a soil sample to the local extension office where they can make a determination about what the soil still may need.
Stevia is not easily grown from seed due to very low germination rates of about 10%. You can start your own seedlings if you are able to obtain high quality seed that is black or dark brown in color. Other colors indicate that the seeds are not viable. It is better to buy transplants from your local nursery or from an online source.
This plant should only be placed in the garden when all danger of frost has past. Cold temperatures or cool nights can halt the growth of the plants. Use row covers if a late frost is expected after the plants are already in the ground. Seedlings should be planted 12 inches apart in rows that are 18-24 inches apart. Growing stevia in small hills is preferred because it helps with the drainage process.
How to Care for Stevia
Make sure that stevia plants get an adequate amount of water. In periods of little rain, they should be watered once or twice per week. The most effective way of doing this is by using a soaker hose in between the rows. This prevents the foliage from getting wet, and prevents the introduction of diseases that stevia plants are prone to.
You should mulch plants lightly after planting, and then apply a thicker layer when the weather becomes hot. If you mulch with grass clippings or compost, they will add nitrogen slowly to plants, which is something that they need. Pinch stems back slightly to encourage bushier growth, and to protect the brittle stems from breakage.
The final process in growing stevia is the harvest. You can use fresh leaves for eating, or for using to sweeten tea. After the season is over, and before plants begin to flower, you can harvest entire plants and dry them. Dried leaves can be ground up for use in recipes calling for ground stevia.
If you are looking for something different to put in the garden, stevia is a good choice. It is a natural sweetener that can be used for multiple purposes. It grows well in containers inside, and also in the garden. Growing stevia can be very challenging but also very rewarding.
Additional Stevia Information and Resources:
Learn more information about Stevia from Washington State University’s Garden Mastery Tips.
The University of Kentucky has created a downloadable PDF report on various aspects of Stevia
Read this Stevia grower’s guide created by Kanas State.