Stevia (Stevia rebaudiana) is unique among herbs.
This plant is not used to flavor food but to sweeten food; it’s an herbal sugar substitute. A member of the chrysanthemum family, stevia was named for Spanish botanist and physician Petrus Jacobus Stevus, a professor of botany at the University of Valencia in the 16th century. It is native to Paraguay and parts of Brazil, where it has been used to sweeten tea and medicine for over 200 years. Today, most stevia is grown in China.
This remarkable plant contains steviol glycosides, compounds that are up to 300 times sweeter than sugar — but without the calories. It is easy to grow and can help you reduce your processed sugar intake. The good news for someone who is diabetic or prediabetic is that stevia does not have a significant effect on raising blood sugar (blood glucose) levels. This property makes stevia very attractive for diabetics on a low-carbohydrate and low-sugar diet, because it satisfies a person’s sweet tooth but doesn’t adversely affect their blood sugar.
Stevia is a plain-looking, woody, perennial shrub with green leaves and small white flowers. It averages 2 to 3 feet tall and 1 to 2 feet wide. It is best grown in larger container pots that can be brought into the house in the winter.
Stevia can be a challenge to grow from seed. They are slow to germinate and have low germination rates, so plant extra in late winter. Keep seedlings at about 75 degrees and under bright lights 16 hours a day for eight to 12 weeks until the outdoor daytime and nighttime temperatures remain warm and all danger of frost has passed. Stevia is very tender and will die with the first light frost.
Stevia grows far better from rooted cuttings. Plants often decline after the second year, so propagating from cuttings from 2-year-old plants works well. Transplant seedlings 18 inches apart.
Stevia needs slow, steady nitrogen for leaves to develop sweetness. Too much nitrogen causes rapid leaf growth but almost no sweetness. To assure lots of tender, sweet leaves, soil should be light and loamy with lots of organic matter and compost for slow, steady growth. Plants need to be consistently moist yet planted in well-drained soil. Plants die very quickly in water-logged soils. The plant benefits from mulch to retain soil moisture.
Cut back leafy growth often to encourage bushy plants. In the heat of summer, provide light or dappled shade in the afternoons.
The sweetest leaves are those harvested in the cool fall weather, before the first frost. Since glycoside synthesis is reduced at or just before flowering, delaying flowering allows more time for glycoside accumulations. Pinch out emerging flowers to alleviate this situation. Once the plant blooms, it stops producing leaves and the remaining leaves turn bitter.
If you grow stevia in containers, right before frost you can cut plants to 6 inches in height and bring them indoors for the winter. However, they need bright light for 16 hours a day and temperatures around 75 degrees, so place them near a south-facing window.
One way to use stevia is to dry the leaves, store them in a glass jar and crush them when needed. Drying will concentrate the sugar. You can also use fresh leaves to make a sweet syrup by chopping about a cup of fresh leaves and pouring warm (not boiling) water over them. Let them steep overnight, then strain and refrigerate. Your syrup can be used to sweeten cold and hot beverages, creamy desserts and yogurt. It will last about a month in the refrigerator.
Chop fresh leaves and add to fruit salad, pasta or vegetables that are not bitter (such as Brussels sprouts) for a sweet herbal flavor. Do not add chopped stevia while food is cooking; wait until right before serving. Dried stevia leaves are 30 to 300 times sweeter than cane sugar, so use a light touch as the leaves may be sweeter than you expect.
By growing this amazing herb you not only get the satisfaction of utilizing your gardening skills, but also get to have foods that are naturally sweetened and healthy to eat. How can you go wrong?
• The WSU Extension Master Gardener Program is an organization of trained volunteers dedicated to horticulture and community service. The Master Gardener Walk-In Diagnostic Clinic operates from 9 a.m. to noon and 1-4 p.m. Mondays, Wednesdays and Fridays. Direct questions about gardening, landscaping or this program to the Master Gardener Clinic at 509-574-1604, or leave samples for identification at the WSU Extension office. Leave a message with your name, phone number, email address and the nature of your problem or question. You can also email your questions to email@example.com and include pictures if you have them. A member of the Master Gardener Clinic team will check voicemails and emails, and reply as soon as possible. The WSU Extension office is at 2403 S. 18th St., Suite 100, in Union Gap. Call 509-574-1600. New volunteers are welcome.