Lemon verbena (Aloysia citrodora) is a woody shrub known for its potent citrus aroma. The leaves are commonly used to infuse teas, flavor culinary dishes, and create natural fragrances due to their high concentration of volatile essential oils. Effective harvesting and preservation methods are necessary to maintain these aromatic compounds, ensuring the herb retains its quality for long-term use. This guide provides steps for collecting and storing the leaves to maximize both potency and shelf life.
Optimal Timing and Pre-Harvest Conditions
The timing of the harvest significantly influences the concentration of aromatic compounds, particularly the aldehyde citral, within the leaves. The highest essential oil content is achieved during the warm mid-summer months when the plant is actively growing. A plant should be fully established and reach a height of at least 10 to 12 inches before any substantial harvesting takes place.
The time of day also plays an important role in the quality of the harvested material. Cut the stems late in the morning or early afternoon after the morning dew has completely evaporated from the foliage surface. Harvesting after the dew dries prevents excess moisture from being trapped, which can lead to mold during the curing process. Conversely, cutting should be completed before the most intense heat of the day begins, which can cause the essential oils to volatilize and dissipate.
Before harvesting, ensure the plant has been adequately watered in the preceding days to support its overall health. The surface of the leaves, however, must be dry at the moment of cutting to ensure successful preservation.
Techniques for Cutting and Pruning
Using the correct tools and technique during the cutting phase is important for both the quality of the harvest and the future health of the plant. Always employ clean, sharp pruners or scissors to ensure a quick, precise cut that minimizes damage to the remaining plant tissue. Dull tools can tear the stems, making the plant more susceptible to disease or weakness.
The physical act of harvesting doubles as a beneficial pruning technique that encourages the plant to produce new, bushier growth. To achieve this, make all cuts just above a leaf node, the small bump where a pair of leaves is attached to the main stem. Cutting directly above this point stimulates the dormant buds to sprout new shoots, leading to a denser, more productive structure.
Limit the amount of material removed in a single session to prevent undue stress on the plant’s system. Never remove more than about one-third of the plant’s total foliage and stem growth at any one time. Adhering to this rule allows the remaining leaves to continue the necessary photosynthesis required for rapid recovery and regrowth. Light harvesting sessions can be repeated throughout the growing season, usually every four to six weeks, provided the plant shows vigorous regrowth.
Curing and Storing the Harvest
Once the lemon verbena has been harvested, proper curing is the next step to preserve its aromatic integrity for long-term use. The most common preservation method is air-drying, which requires bundling the cut stems together with twine. Hang these bundles upside down in a dark, warm environment that offers excellent ventilation. Excluding light helps prevent the breakdown of sensitive compounds.
Air circulation is necessary to wick away moisture quickly and evenly. Monitor the bundles during the first few days to ensure no moisture pockets remain, which could promote mold growth. Alternatively, a food dehydrator can be used for a faster process, setting the temperature to a low setting, typically between 95°F and 105°F (35°C to 40°C).
The leaves are sufficiently dried when they easily crumble to the touch, indicating all moisture content has been removed. After the leaves are completely dry, carefully strip them from the woody stems, which are typically discarded. Storing the leaves whole is preferable to crushing them, as this minimizes the surface area exposed to oxygen and helps retain the volatile oils for a longer duration. The final storage location should be in an airtight container, such as a glass jar, away from direct light and heat sources. Properly stored, dried lemon verbena can maintain its quality and potent fragrance for up to one year.