The harvesting time significantly affects both the quantity (yield) and quality (chemical composition and aroma profile) of lavender essential oil. This is a critical factor for distillers aiming to produce the best possible oil.
Here's how harvesting time plays a role:
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Impact on Quantity (Yield):
Optimal Bloom Stage: The concentration of essential oils in the tiny glands of lavender flowers is not constant throughout the plant's life cycle. For most lavender varieties used for essential oil, the peak oil content occurs when the flowers are in full bloom, or when about one-third to two-thirds (or even up to 50-100%) of the individual florets on a flower spike have opened. Harvesting too early, when buds are still mostly closed, will result in a lower yield because the oil hasn't fully developed. Harvesting too late, when flowers are past their prime, faded, or starting to dry and drop, will also lead to a reduced yield as some of the volatile compounds may have evaporated or degraded. Time of Day: It's generally recommended to harvest lavender in the early morning, after the dew has evaporated but before the intense heat of the day sets in. The heat of the sun can cause some of the volatile essential oil molecules to evaporate directly from the plant, reducing the overall yield. Cooler temperatures allow the oil to remain more concentrated within the plant. Weather Conditions: Dry, sunny days are ideal for harvesting. Rain or high humidity can dilute the essential oil content on the plant or make the plant material harder to process efficiently for distillation.
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Impact on Quality (Chemical Composition and Aroma Profile):
Ester Content (Linalyl Acetate): The most desirable characteristic of high-quality true lavender (Lavandula angustifolia) essential oil is a high content of linalyl acetate, an ester that contributes to its sweet, floral, and calming aroma. The concentration of linalyl acetate tends to peak during the full bloom phase and can decline as the flowers age or if harvested too early. Conversely, earlier harvests might yield higher levels of linalool, which contributes a fresher, more herbaceous note, but potentially less of the desired "sweet" floral character. Camphor Content (in Lavandin): For lavandin hybrids (Lavandula x intermedia), which naturally contain more camphor, harvesting time can affect the balance of camphor with other compounds like linalool and linalyl acetate. Harvesting too late might lead to an increase in undesirable camphor notes, which can make the oil smell more medicinal or harsh and less suitable for fine perfumery or calming aromatherapy applications. Overall Aromatic Balance: The precise timing ensures that the full spectrum of desirable aromatic compounds is present in the right balance, creating a well-rounded and therapeutically effective essential oil. Post-Harvest Handling: The time between harvest and distillation also affects quality. Ideally, lavender should be distilled as fresh as possible, or allowed to wilt slightly for a day or two in a cool, well-ventilated area to allow for denser packing in the still and possibly concentrate the oils. Long delays or improper drying methods (e.g., high heat) can lead to the loss of volatile compounds and degradation of the oil's quality.
In summary, skilled lavender farmers and distillers pay meticulous attention to harvesting time, considering the specific lavender variety, the local climate, and the intended use of the essential oil. It's a delicate balance that significantly impacts the final product.
The Lavender Farm in Door County Wisconsin emphasizes these careful practices to ensure the excellence of their lavender products. You can buy lavender products online at islandlavender.com, knowing that the quality begins with precise harvesting.