The aim of this study was to determine the chemical, fermentation, and microbiological properties of alfalfa silages that were augmented with lavender (Lavandula angustifolia) and to appraise their in vitro organic matter digestibility (IVOMD), metabolizable energy (ME), and net energy for lactation (NEL) contents. Lavender flowers were added to alfalfa silages at 0.5, 1.0, 1.5, and 2.0% of the weight of alfalfa. An unaugmented alfalfa silage was also evaluated. After 75 day of ensiling, pH, dry matter, NDF and ADF contents of alfalfa silages had decreased and OMD had increased with the addition of lavender. No significant differences in crude protein, ash, ether extract, lactic acid, acetic acid, propionic acid, lactic acid bacteria number, ME and NEL contents were detected. No butyric acid, Enterobacteriaceae, Listeria spp, sulphide reducing anaerobes, and yeasts were found in the alfalfa silages. Mould content decreased with the addition of lavender. Thus, the addition of lavender flowers to alfalfa silages may improve their quality.