Stevia is a natural sweetener derived from the leaves of the Stevia rebaudiana plant. The sweetness comes from compounds known as steviol glycosides, which can be hundreds of times sweeter than table sugar but contain no calories. Processing the leaves at home involves harvesting, drying, and preparation. This guide provides the steps necessary to properly harvest and cure the leaves to maximize the sweetness for at-home use.
Identifying the Optimal Time for Harvesting
The concentration of sweet steviol glycosides is highest in late summer or early autumn, just before the first expected frost. Cooler temperatures during this period cause the plant to intensify its sweetness as it prepares for the end of the season.
The most important indicator to watch for is the development of flower buds. Once the plant begins to flower, its energy shifts away from leaf production, causing the stevioside content to drop significantly, and the leaves can even develop a slightly bitter flavor. Pruning the plant throughout the season to prevent flowering will encourage a bushier habit and a greater overall leaf yield. When harvesting, it is best to collect the leaves in the morning, after the dew has evaporated.
Proper Cutting Techniques
Selecting the correct cutting point is important for encouraging regeneration. Using sharp shears or clean scissors, cut whole branches from the main plant. Avoid tearing the stems, as a clean cut promotes faster healing.
Never remove more than one-third of the plant’s foliage at any one time to ensure the plant can continue to grow and produce more leaves. Make the cuts high enough on the stem to leave at least 4 to 6 inches of growth above the soil. This remaining portion allows for new shoots to sprout from the leaf nodes, providing a continuous supply of fresh leaves for future harvests until the frost arrives. The large final cut yields the greatest bulk of sweetener.
Curing and Drying the Leaves
The curing and drying process removes the leaves’ moisture and concentrates the sweetness. The stems or individual leaves should be placed in an environment that is warm, dark, and well-ventilated. Exposing the leaves to direct sunlight during drying can degrade the sweet compounds and lead to a loss of potency.
Gather the cut stems into small bundles and hang them upside down in a sheltered location. Alternatively, individual leaves can be stripped from the stems and spread in a thin, single layer on a fine mesh screen or drying rack to ensure maximum air circulation. The drying time should be as quick as possible, ideally less than twelve hours, to prevent the breakdown of steviol glycosides. The leaves are considered completely dry when they feel brittle and crumble easily between the fingers.
Storage and Preparation for Sweetener Use
Once the leaves are thoroughly dry, they should be stripped from the stems. The dried leaves must be stored correctly to maintain their potency and prevent degradation. They should be placed in an airtight container and kept in a cool, dark place away from any heat source. Stored this way, the dried leaves can retain their sweetness for a year or more.
The dried leaves can be processed into a usable sweetener in two main ways. The simplest method is to crush the leaves into a fine, green powder using a mortar and pestle or a dedicated spice grinder. This powder can be used directly as a sugar substitute in baking or sprinkled into foods, though it will not dissolve in liquids like refined sugar. For a liquid sweetener, the dried leaves can be steeped in hot water or a mixture of alcohol and water to create a concentrated liquid extract.