Grow, Harvest, and Use Naturally Sweet Stevia

An herb that grows in the garden and can be used as a sugar substitute sounds too good to be true, so of course I had to try it. Naturally sweet stevia has now taken its place on my list of must-grow herbs.

Stevia (Stevia rebaudiana) is a member of the chrysanthemum family. It is native to South America, where it grows as an evergreen shrub. In temperate zones, however, it can be grown as an annual (zones 1-8) or tender perennial (zones 9-11).

Growing Stevia

Growing stevia from a cutting is easier than starting from seed. Some nurseries and big box stores offer started plants in the herb department. Since I don’t have a ready source for cuttings or plants, I chose the seed route.

Because starting stevia from seed can be difficult, I start mine indoors. Stevia seed, like lettuce seed, needs light to germinate. I use tweezers to drop 3 or 4 seeds into each pot filled with moistened soil. I gently press the seeds into the soil, then cover them with a thin layer of vermiculite to retain moisture.

Then I heavily mist the surface, cover the pots with clear plastic, and place them under grow lights, timed to allow 8 hours of darkness each night — just like in the real world. Every morning I spray the soil surface to keep the seeds moist.

In 10 days to 2 weeks the seeds germinate. Well, at least some of them do. The first time I grew stevia, only two seeds sprouted out of 18. But both grew into healthy plants that provided more leafy sweetener than I could use until the next harvest. But I’m getting ahead of myself.

After all danger of frost has passed, the soil temperature is above 50ºF, and the air temperature is in the 70s, I transplant the seedlings into a sunny place in my garden. I space the plants about 18 inches apart. From then on it’s just a matter of watering them frequently, but lightly. Stevia does not like a soggy bottom.

In 3 months or so, the plants grow to a height of about 30 inches. At this point I keep a close eye on them to make sure they don’t bloom. As soon as flowers appear, the leaves start losing sweetness.

Harvesting Stevia

Stevia leaves are sweetest when harvested during the cool days of autumn. The plants are frost tender, so where I live they must be harvested before the first frost.

To dry the leaves, cut down the plants and spread the stems on baking sheets. Place the baking sheets in the oven, with the light on and the door ajar, and stir them once or twice a day. When the leaves are brittle dry, strip them from the stems, place them in tightly sealed jars, and store them in the pantry or other cool, dark place.

Because the plants produce such an abundance of leaves, I don’t need to grow stevia every year. If you want to grow it two years in a row, you can start cuttings in pots, to be transplanted outdoors the next spring.

Using Naturally Sweet Stevia

Stevia grown in your garden differs from stevia sold at the grocery. Store-bought stevia is in extract form, often combined with other things you may or may not want to consume.

Stevia leaf is a non-caloric sweetener. It also has a stable shelf life. It offers several health benefits, along with having possible downsides, although I’ve seen no scientific proof of issues related to whole-leaf stevia used in moderation. (Who’s going to eat stevia by the spoonful?)

Some people claim stevia has a mild, licorice-like flavor, but I haven’t found that to be true. It does have a slight, but not unpleasant, bitterness — it’s more an herbal quality than truly bitter. On the other hand, apparently not all stevia plants taste alike.

The first two plants I grew looked entirely different, too. One was tall and rangy, the other squat and bushy. But both tasted the same to me. Now I just blend together all the leaves from all the plants harvested in the same season.

To use stevia as a sweetener, fill a blender about half full with dry leaves and process at high speed for a few seconds. Store the powdered sweetener in an airtight container.

I use stevia leaf powder mostly in pickling and tomato based recipes to balance acidity, in place of sugar. If you like sweetened tea or coffee, stevia is suitable for that, too, as well as for sweetening lemonade and smoothies.

Stevia is unsuitable in recipes for which the melting properties of sugar contribute to the food’s structure, such as in jams and jellies, or cookies and other baked goods. Since stevia is non-fermentable, it’s not a reasonable sugar substitute for bottling beer or soft drinks.

Stevia leaves get their sweetness from glycosides, which are compounds containing a carbohydrate (sugar) element bound to a non-sugar element. Compared to table sugar, whole-leaf stevia is said to be 30 times sweeter. A little naturally sweet stevia goes a long way, so start with a pinch, taste test, and go from there.