Stevia is a non-caloric natural sweetener derived from the leaves of Stevia rebaudiana, a plant native to Paraguay and Brazil. The sweetness comes from steviol glycosides, compounds hundreds of times sweeter than table sugar. This tender perennial herb has been used for centuries by the Guaraní people to sweeten beverages like yerba mate. Growing Stevia offers the home gardener a direct source of this sweetener, providing an alternative to processed sugar substitutes.
Site Selection and Initial Planting
Starting Stevia successfully begins with choosing the right method, as growing from seed is notoriously challenging. Stevia seeds have a low germination rate (often 10% to 40%), and resulting plants may lack the desired sweetness. The preferred method is to start with purchased transplants or rooted stem cuttings, which ensure the plant is a true clone of a sweet variety. Cuttings establish a robust root system much faster than seeds, typically being ready for the garden in four to six weeks.
Stevia requires full sun (at least six hours daily) to promote the highest concentration of sweet compounds in the leaves. It thrives in well-draining, loamy soil; waterlogged conditions quickly lead to root rot. The ideal soil pH is slightly acidic to neutral (6.7 to 7.2).
For containers, select a pot at least 12 inches in diameter to accommodate root growth. Ensure the container has ample drainage holes to prevent water accumulation. For in-ground planting, space plants about 18 inches apart, and amend the soil with organic matter like compost to improve drainage and nutrient content.
Watering, Feeding, and Seasonal Care
Stevia requires consistent moisture, especially when establishing young plants and during the peak heat of summer. Keep the soil moist but never soggy, as the plant is highly susceptible to root rot. Check the soil with your finger; if the top inch feels dry, water thoroughly until you see water draining from the bottom of the pot.
Stevia is not a heavy feeder; too much nitrogen is detrimental to leaf quality. Excessive nitrogen encourages vigorous green growth but dilutes the steviol glycosides, reducing sweetness. Apply a dilute, balanced organic fertilizer or compost tea every four to six weeks, especially for container-grown plants.
Regular pruning maximizes harvest by encouraging bushy, lateral growth. When the plant reaches about eight inches tall, pinch off the top set of leaves and stem tips to promote side branching. Continuing this pinching throughout the growing season results in a denser plant with a greater yield of harvestable leaves. Stevia is a tender perennial sensitive to cold, so it must be treated as an annual in regions that experience frost.
Harvesting for Maximum Sweetness and Storage
Timing the harvest is important for securing the sweetest leaves, as the concentration of steviol glycosides fluctuates. Leaves reach peak sweetness just before the plant begins to flower, typically in late summer or early fall. Allowing the plant to flower diverts energy away from sweet compounds and can introduce a slightly bitter flavor.
The main harvest should take place before the first expected frost, ideally on a dry morning after the dew has evaporated, when the sugar concentration is highest. To harvest, cut the entire stem, leaving four to six inches above the soil line for potential late-season regrowth. Individual leaves can be picked throughout the season, but cutting whole stems provides the largest yield for preservation.
To preserve sweetness, the leaves must be dried quickly to prevent mold. Strip the leaves from the harvested stems and spread them in a single layer on a screen or cloth in a warm, dark, and well-ventilated location. Drying is complete when the leaves are brittle and crumble easily, which can take several days depending on humidity. Alternatively, a food dehydrator set between 95°F and 115°F achieves faster, more consistent results.
Once fully dried, store the whole leaves or crush them into a coarse powder. Place the dried material in an airtight container, such as a glass jar, and keep it in a cool, dark place to protect the sweet compounds from light and humidity. A liquid extract can also be made by soaking the dried leaves in a food-grade solvent like vodka or hot water, creating a concentrated sweetener.
Propagating and Overwintering Stevia
Propagating Stevia from stem cuttings is an effective way to ensure a supply of sweet plants for the next season. In late summer, take four-to-six-inch cuttings from healthy stems, cutting just below a leaf node, and remove the leaves from the bottom two inches. Dipping the cut end into a rooting hormone powder can expedite the process, but it is not necessary.
Place the prepared cuttings in a moist, sterile rooting medium, such as a mix of perlite and peat moss, and keep them in a bright location out of direct sun. Roots develop within a few weeks, and the new plants can be potted up once a robust root system is visible. For gardeners in colder climates, preserving the parent plant through the winter ensures a head start the following spring.
Before the first frost, prune the mature Stevia plant back to about six inches and transplant it into a container with drainage holes. The plant should be moved to a sunny indoor location, ideally where temperatures remain above 60°F. During this period, the plant enters a semi-dormant state, requiring significantly less water and light until it can be safely moved back outdoors after all danger of frost has passed.