Stevia

If you have never tasted a stevia leaf, you probably won’t believe the level of sweetness this herb provides. It just doesn’t seem possible. A single, delicate green leaf placed on the tongue does nothing. Start chewing and you’d swear you just downed a spoonful of sugar! Let’s find out if this is a plant you can add to your garden or foodscape.

Stevia (Robert Lynch) Public Domain

Native to Paraguay and the surrounding tropical regions, stevia (Stevia rebaudiana) is also known as sweetleaf. Stevia is the model used to create several ‘natural' sweeteners, except that most of them are not what we gardeners would think of as natural.

​The majority of these stevia plants are grown in China and the leaves are so highly processed that there is little left besides the sweetness. [Being 200 times sweeter than sugar, stevia packs a powerful sweetness punch, processed or not.] Using the unprocessed leaves as a sweetener, on the other hand, adds several different compounds, called glycosides, plus antioxidants, and we all need those!

​The stevia plant

​Being a tropical member of the sunflower family, stevia loves the heat. This tender perennial prefers USDA Zones 9 - 11, and is grown as an annual elsewhere. Stevia grows best under the same conditions as basil.  Like basil, stevia needs some protection from the high heat of our California summer. Plants can reach 1 to 4 feet high and wide, depending on temperatures and the local microclimate.

Flowering stevia (Ethel Aardvark) CC BY 3.0

How to grow stevia

Stevia plants can be grown from seed, but results are hit-and-miss, as germination is tricky. If you decide to try your hand at seed starting stevia, begin indoors, 8 to 10 weeks before your last frost date. Seeds germinate best at temperatures between 68 and 75°F. Fill pots with a light potting soil or peat mixture. Press seeds into the soil and cover with perlite. This will protect seeds from the air and help the soil retain moisture, but provide seeds with the light they need to germinate. To avoid flooding seeds into the corners, water by misting heavily, at first.

Like peppers, stevia plants benefit from the use of a waterproof germination mat. This gives them the heat they need to get started. Cover the pots with plastic and check twice a day to ensure that the top 1/2-inch of soil remains moist until germination occurs, which should take 10 to 15 days.

Stevia needs well-drained soil. This makes them an excellent choice for large containers or raised beds, where high quality potting soil provides plenty of macropores and micropores in the soil. During summer heat, these plants need almost daily watering. Allow the soil to almost go dry before watering again.

If you allow your stevia plants to go to seed, you can collect seed heads or let them grow where they fall. If you collect the seeds, discard light-colored specimens, as they are probably not viable. Most often, new plants are started from rooted cuttings.

Stevia pests and diseases

Outside of greenhouses, cutworms and sugar addicts are stevia’s only serious threats. In close quarters, aphids, whiteflies, and thrips can can become a problem.

Harvesting stevia

You can use stevia leaves fresh from the plant or you can harvest and dry them for later use. The sweetness remains unchanged in either case. Leaves are at their sweetest just before flowering. Once the plant flowers, leaves do not taste as good or as sweet. Each plant can provide you with approximately 1/2 pound of dried leaves each year.

Using stevia

Stevia is used to sweeten teas and other beverages, fruits, yogurt, custards, salad dressings, and many other liquid-based foods. Stevia can be used to replace some, but not all, of the sugar in baked goods. [Sugar has certain chemical properties that are needed in baking that stevia cannot provide.]

Before adding even more sugar to your diet, how about adding stevia to the garden, instead?