As for essential oils that have long shelf lives usually, they are the thicker ones, such as Cedarwood, Sandalwood, Patchouli, Vetiver and a few others. Exception to this thick oil quality will be the essential oil of Rose Otto.
The season for them is generally a short one. Begins in early July and last for 2 to 3 weeks. Black raspberries tend to ripen before most red raspberries varieties expect for the early ripening summer ones.
There are two categories of Raspberries, the common raspberry, which ripens in early to midsummer, and the so called everbearing Raspberry. Unlike everbearing Strawberries which produce fruit continuously over the summer, the everbearing Raspberry produces an early-summer crop on the previous season's growth. and a fall crop on the current season's growth.