Properly storing your essential oils is great for longer shelf life and safety. Essential oils are volatile which means they escape in the air when they are open or exposed, keeping them in the dark and properly sealed is optimal.
Essential oils should be stored in a cool dark place, out of sunlight and out of reach from children and animals. Fluorescent and Artificial light shortens the life of your essential oils. Purchasing your essential oils stored away from the display is better and not under sunlight or artificial light which is usually common in stores.
Putting essential oils in plastic is not recommended, especially undiluted. Essential oils diluted in soaps and shampoos which are stored in plastic should be fine but undiluted oils break down plastic.
Essential oils such as citrus oils (such as grapefruit, orange, lime, mandarin, and lemon) and conifers and firs (such as fir, pine, and cypress) have a shorter shelf life in general. Citrus oils are highly volatile which leads to faster oxidation, causing them to lose their characteristic therapeutic properties, actions, and effects.
Since Citrus oils are the most volatile of all the essential oils, you will need to take special care of them by tightly sealing and storing them in a darkened area that is both dry and cool. You can limit the amount of oxidation of your essential oils by keeping them in bottles that are filled to capacity in which there is no room inside the bottle for oxidation to occur.
You can consider refrigerating your citrus oils, blue oils, conifers, and others to increase shelf life as long as the oils are kept in a dry condition and are stored for long-term use rather than being dispensed daily.
Make sure you have a separate fridge as once again the oils are volatile and guess what? If you use your personal fridge your food will begin to smell like oils.
Do not refrigerate rose oil, as it will thicken and congeal. Thicker, viscous oils have a low volatility rate and, as long as the bottle is filled to capacity, will have a very slow oxidation rate.
Refrigerating your blue oils will help them retain their vibrant blue color.