Lavender is a highly popular aromatic herb used globally, valued for its distinct floral scent and calming properties derived from volatile essential oils. When people ask if lavender “goes bad,” they are usually asking about the loss of its beneficial aroma and therapeutic potency, rather than traditional spoilage like mold or rot. Pure lavender products do not spoil in the manner of food, but they do undergo chemical degradation over time. The rate at which the herb loses its useful qualities depends entirely on the form it takes.
Shelf Life Varies by Lavender Form
The shelf life of lavender is determined primarily by whether it is a dried flower or a concentrated essential oil. Dried lavender flowers or buds are generally the most resilient form, retaining their strong fragrance for approximately one to three years when stored correctly. The primary mechanism of degradation in dried flowers is volatilization, which is the slow evaporation of aromatic compounds. Essential oil, which is a highly concentrated extract, typically maintains its purity for three to four years, and possibly longer if stored perfectly. However, the oil’s degradation mechanism is predominantly oxidation, where chemical components react with oxygen, reducing the oil’s therapeutic value and safety over time.
Factors Accelerating Degradation
The chemical breakdown and loss of quality in all lavender forms are accelerated by exposure to environmental factors. Oxygen is the primary catalyst for oxidation in essential oils, creating new compounds that are less fragrant and potentially irritating. Essential oils are highly sensitive to light, especially ultraviolet (UV) rays, which cause photodegradation by breaking down chemical structures. Heat greatly increases the rate of both volatilization and oxidation, diminishing aromatic strength. For dried lavender, moisture is a major threat, leading to true spoilage via mold or mildew growth, so proper storage minimizes contact with these accelerating factors.
Practical Indicators of Lost Quality
Consumers can use their senses to determine if lavender products have lost quality. For dried lavender, the most obvious sign of degradation is a significant loss of the characteristic floral scent. The color of the buds may also fade over time, changing from vibrant purple to a duller grey or brownish tone. If the dried material has been improperly stored, a musty or unpleasant odor can indicate mold growth. For essential oil, the change in aroma is the most reliable indicator of oxidation, where the fresh, sweet scent may become fainter, or develop a sharp, unpleasant, or metallic smell. Changes in physical appearance also signal degradation, including:
- The oil becoming noticeably thicker or cloudier.
- The formation of sediment at the bottom of the bottle.
Safe Use of Aged Lavender
The safety implications of using aged lavender differ significantly between the dried herb and the essential oil. Dried lavender that has simply lost its scent is generally safe for continued use in sachets or culinary applications, provided there is no visible mold or mildew. Mold or mildew, which occurs if the product was exposed to dampness, makes the dried herb unsafe for consumption or close contact. Aged lavender essential oil poses a distinct health risk because of the chemical changes resulting from oxidation. The primary component in lavender, linalool, can break down into compounds like linalool hydroperoxide when exposed to oxygen. These breakdown products are known to significantly increase the risk of skin sensitization, irritation, and allergic reactions when the oil is applied topically. Therefore, if a bottle of lavender essential oil has developed a noticeably unpleasant odor or is past its recommended shelf life, it should not be used on the skin. Oxidized oil can still be used for simple aromatic purposes, such as diffusion, where skin contact is avoided.