Does the cannabis plant material or trimmings have to be dried before using them in cooking?
Well, I would not go straight from the garden to the cooking vessel. You want it at least dry enough to break it/crumble it small pieces. So while a full cure like would do if you intend to smoke it is not absolutely necessary, you will at least want to let it air dry for a few days or even a week or more depending on the humidity in your area.
It is advantageous to get as much moisture out before infusing in butter and oils as moisture can invite mold later on. Yes, there is a technique for making infusions with water , but that’s another topic (check out the link if you are interested in that), but generally speaking, keeping water out is a good idea.
With fresh material, especially, decarboxylating first is important. That’s because with age and proper curing, some decarboxylation does naturally occur, and more will happen during cooking. But when you are using fresh plant material, none of that will have happened. Also some drying will occur during the process of decarbing.
If you don’t know what decarboxylation is or how to do it check out this link.
So the bottom line is, for best results, dry the plant material, but you don’t need to do a full cure, decarboxylate, and you are ready to start cooking!