Storage after Packaging
Storage of hydrosols after sterile bottling should be the same as for bulk storage: a cool or cold and constant temperature, away from heat and light.
Treat hydrosols like you would milk or a bottle of mineral water. If you drink half a bottle of mineral water and leave it in the car for two weeks, do you want to drink it again? It's just common sense.
Treat hydrosols with a little respect and they will stay fresh for at least eight months and for up to two years or more from day of distillation.
Reference: Hydrosols The next aromatherapy: Suzanne Catty