I recently saw a very funny television commercial about Splenda Naturals brand Stevia called “The sweetest thing you COULD grow” (see below). I laughed pretty much all the way through.
The premise is that you could grow stevia yourself, but it’s such a bother when you could simply open a pack of Splenda stevia and pour it into your ice tea. One character says about growing stevia, “I mean, if you had time, and you liked gardening, and—you know—you liked kinda doin’ stuff the hard way.”
And it’s sooo true … except that gardeners do like gardening and they do like “kinda doin’ stuff the hard way.” Plus, growing stevia really isn’t that hard!
So, the commercial backfired with me. It simply made me want to grow stevia even more, thus thumbing my nose at big business. And besides, I already grow stevia and have for years.
What Is Stevia?
Stevia may be a commercial sweetener these days, but it was originally a plant: Stevia rebaudiana, from the Asteraceae family. You may hear it called sweet leaf, sweet herb, honey leaf or candy leaf. It’s named after Pedro Jaime Esteve (1500–66), a Spanish physician and botanist, while the epithet rebaudiana comes from Dr. Ovid Rebaudi, the 19th-century Paraguayan chemist who first extracted the sweet constituents from the plant.
It hails from South America and has been used for some 1500 years by the Guarani people of Brazil and Paraguay who call it “ka’a he’ ẽ” (“sweet herb”). They use it to sweeten bitter foods and medicines and as a snack. It contains glycosides like stevioside and rebaudioside that repel insects (yes, the plant concocted them as natural insect repellants!), but fresh leaves also have 10 times the sweetness of sugar. (Commercial stevia concentrate can be 300 times sweeter than sugar!) Humans can taste the sweetness, but can’t digest the glycosides. And that means stevia is a natural sweetener with essentially no calories, which is why stevia is so often of interest to people wishing to reduce their caloric consumption.
The plant is a small shrub about 30 to 80 cm (1 to 2.5 feet) in height with oblong, mid-green, slightly hairy opposite leaves with prominent veins, a lightly toothed margin and a very short, sometimes absent petiole. It grows upright at first, but older stems, green at first, eventually turning woody, bend and wander if you don’t cut them back. Clusters of tiny white flowers are produced in the late fall or winter, as it is a short-day plant. They aren’t particularly attractive and it’s probably best to remove them.
Despite its subtropical origin, stevia is easily grown in temperate climates as an annual. Or indoors as an edible houseplant. And it basically needs only the same care you’d offer to just about anything else you’d grow.
Plant stevia plants outside in late spring when both the soil and the air have warmed up… about the same season you would plant out tomato or peppers. Place them in full sun to very light shade in good garden soil: well drained, evenly moist, with a pH ranging from acidic to alkaline (5 to 8), although a range of 6.7 to 7.2 is best. In other words, your vegetable or flower garden would probably be perfect, as would any potting soil.
Space the plants about 20 to 25 cm (8 to 10 inches) apart and keep them evenly moist. Mulching can help with that and you’ll likely need to water during times of drought. Container plants dry out faster than garden plants, so keep a special eye on them.
Whatever fertilizer or compost you apply to your other garden plants will suit stevia just fine. There is no need to fertilize abundantly: as with most herbs, the taste is more concentrated when the plant is a bit underfertilized.
Stevia is not frost hardy and will not survive outdoors in temperate climates. It will live on in USDA hardiness zones 9 and above, and sometimes even 8, as it will grow back from the base if only the leaves are frosted. Prolonged freezing, though, will kill it.
Stevia grows readily indoors provided you offer it quite intense light. A sunny windowsill or a place under fluorescent or LED grow lights will suit it wonderfully.
In natural light, it will probably etiolate somewhat during the short, gray days of winter, but you can then simply prune it back. It will start to look better when a burgeoning spring brings more sun.
Watering is as for almost any houseplant: when the potting mix is dry to the touch, water thoroughly with tepid water. How often you need to water will depend on your growing conditions as well as the size of the pot (large plants in small pots will need more frequent watering).
Stevia wilts rapidly when its soil is dry, but will recuperate if you catch it before it goes too far. Still, letting it dry out with any frequency is not a good idea, as each drought session weakens the plant. In fact, underwatering is second-biggest cause (after lack of light) for failure with this plant.
It seems to be very resistant to insects and diseases, so no worries there.
Normal home temperatures are fine. Stevia prefers a fairly humid atmosphere, but will survive dry indoor air. Just about any fertilizer will do: apply it during the spring and summer months.
Repot annually, as the plant does spread through offsets and will eventually fill its pot. When you find yourself needing to water more than once a week, you can be sure your plant needs more root room.
Stevia is not a long-lived plant and diminishes in quality after two or three years, after which time it’s best to start new ones.
And taking stem cuttings is probably the best way to go. This can be done at any season, but most gardeners will probably root stems from garden plants in early fall in order to bring young plants indoors for the winter. Apply a touch of rooting hormone to the cut stem and root the cuttings in ordinary potting mix kept slightly moist under clear plastic dome or inside a clear plastic bag. You can also root stevia in water, but then its long-term success rate is much lower.
Alternatively, you can also divide mature plants and pot up the divisions.
As for growing it from seed, well…
First, you probably won’t be able to grow stevia from seed you harvested yourself. Cross-pollination is necessary for the flowers to produce seeds, so you’d need two different clones … and most nurseries sell cutting-grown plants that are all identical. Also, in most climates, your plants will be indoors at blooming time (October through December in the Northern Hemisphere), so pollinating insects won’t reach them. Thus, seed production isn’t too likely.
Secondly, commercially produced seed, while sometimes available, is very hard to germinate. Stevia is probably in fact among the most difficult herbs to grow from seed. Try sowing the seeds on the surface of a damp, sterile seed mix. Press lightly, but don’t cover with mix. Do cover the tray with a clear plastic dome. Bottom heat is essential: use a heat mat. And expose the tray to light, also needed for germination.
Even under those conditions, expect only a minority of seeds to sprout.
So… I suggest reconsidering starting plants from seed: cuttings or division really are the ways to go.
You can harvest and use leaves at any time for fresh eating, but the taste is most concentrated in autumn, just before the plant blooms. If you are growing stevia with the intention of drying it (which concentrates the sweetness even more and makes it possible to store it), fall would be the logical season to do so.
The easiest way to harvest stevia is to cut off a few stems, leaving about 10 cm (4 inches) at the base so it can grow back, then strip off the leaves. The soft stem tip is also edible.
I’m more a gardener than a cook, so make only a limited use of stevia leaves. Most often, I eat it fresh, as a snack, often with my grandkids. I’ve told them it’s called “sweet leaf” and they really bought into that. I haven’t yet convinced them that it replaces dessert, but I’m working on it.
Of course, stevia can be used much more widely than that. It’s popular as a replacement for sugar in tea, coffee, lemonade and other drinks, you can sprinkle it on hot and cold cereals or add it to smoothies and yoghurt. It’s also used in baking of all kinds: 1 teaspoon of dried crushed Stevia leaves equals about 1 cup of sugar. However, you’ll have to seriously modify any favorite recipes, as stevia may replace sugar’s sweetness, but it can’t replace its volume and texture.
Besides being very sweet, stevia leaves do have a slight aftertaste, rather like licorice, a flavor that has been removed from commercial concentrates. Some cultivars with a reduced aftertaste, like ‘Sweetie Star’, are available. Check with a local herb grower for their recommendation.
As Splenda suggests, stevia is certainly “the sweetest thing you COULD grow,” but I disagree with the company in one regard: I think you SHOULD grow it. But still, thanks so much to Splenda for the amusing commercial!