Lavender, prized for its soothing aroma and therapeutic properties, owes its value to volatile oils like linalool and linalyl acetate. These aromatic compounds are highly susceptible to degradation from light, heat, and moisture. Preserving the potency and characteristic fragrance requires deliberate preparation and appropriate storage environments. Proper methods ensure the plant’s beneficial components remain intact, whether stored as dried flowers or in a concentrated liquid form.
Pre-Storage Preparation: Drying the Plant Material
The process of preserving lavender begins with harvesting at the optimal time to maximize the concentration of its fragrant oils. The ideal moment is when the flower buds are just starting to open, typically when about 40 to 50 percent of the buds on the stem are in bloom. Harvesting on a dry day, after the morning dew has evaporated, is important because any surface moisture increases the risk of mold during the drying phase.
Air drying is the traditional and preferred method for preserving the plant’s aesthetic and aromatic qualities. Stems should be gathered into small, loose bundles, secured, and hung upside down in a dark, dry, and well-ventilated space. The darkness helps the flowers retain their vibrant color, while hanging them upside down maintains the straightness of the stems.
For a faster process, a food dehydrator can be used, set to a low temperature, ideally between 95°F and 100°F. The goal is complete dehydration, which is indicated when the stems snap easily and the flower buds feel brittle. This thorough drying is necessary before long-term storage, as any residual moisture will lead to mold growth and ruin the harvest.
Storing Dried Lavender Buds and Flowers
Once the lavender is completely dry, storing the buds and flowers in the right container is paramount to retaining the volatile oils. The best storage location is cool, dark, and dry, which limits the effect of heat and light on the aromatic compounds. Exposure to light causes both the color and the scent to fade more quickly.
The material of the storage container directly impacts the longevity of the fragrance. Airtight glass jars or metal tins are significantly superior to plastic containers, which are not chemically inert. Volatile lavender oils can interact with and degrade certain plastics, potentially leading to the absorption of the fragrance by the plastic itself.
Glass, being non-porous and non-reactive, forms a better barrier against air and moisture, preventing oxidation of the essential oils. Oxidation is the primary chemical process that causes the scent to diminish. Using an airtight seal in a non-reactive vessel locks the fragrant compounds inside, maximizing the shelf life of the dried material.
Storing Lavender Essential Oil
Storing the concentrated essential oil requires different precautions than the dried plant material due to its liquid, highly volatile nature. Essential oil must always be kept in dark glass bottles, such as those colored amber or cobalt blue. The dark tint is necessary to filter out ultraviolet (UV) light, which rapidly breaks down the oil’s delicate chemical structure.
Heat is another major accelerant of degradation, so oils should be stored in a consistently cool place, ideally at or below room temperature, around 60–72°F. Placing the bottles away from direct sunlight, heat vents, or hot appliances minimizes thermal stress on the oil. High temperatures cause the oil’s volatile components to evaporate more quickly, reducing its potency.
The bottle must be tightly sealed immediately after each use to prevent exposure to oxygen. Oxygen initiates oxidation, which alters the oil’s chemical composition and can change its aroma from fresh and floral to a sharper, more medicinal scent. Minimizing the air space, or “headspace,” above the oil further helps to slow this degradation.
Shelf Life and Degradation
When stored in ideal conditions, dried lavender buds and flowers typically maintain a strong, appealing fragrance for two to three years. However, the material can retain a subtle scent and visual appeal for much longer. The primary signs of degradation in dried lavender are a significant loss of the characteristic scent or a noticeable fading of the purple color caused by light exposure.
The presence of moisture will quickly lead to spoilage, which is indicated by the dried material developing a musty odor or visible mold. Lavender essential oil is relatively stable and, if stored correctly, can maintain its quality for three to five years. The first sign that an essential oil has degraded is a change in its physical properties, such as the aroma becoming “off,” or the oil appearing cloudy or thicker than normal.