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.
Once they are planted, raspberries are low maintenance fruits but they do require attention a few times during each season. Pruning is required once a year at different times for autumn and summer fruiting raspberries. Raspberries are water hungry plants so mulching at the beginning of each season is advised. In dry weather they will require watering especially when the fruits are forming. Feeding is also needed. Summer fruiting raspberries will need to be tied into supports during the year.