Containers should be airtight and block out light. Those glass mason jars, while airtight, let in light, so consider changing containers or blacking them out in some fashion. (There are sleeves for jars made of wetsuit materials such as neoprene that both block out light and give the glass an added buffer against bumps and drops.) Dropping in a Boveda pack helps regulate humidity—too much moisture in a sealed jar will result in mold, but if there's not enough, it will get so dry that it'll crumble when touched.
Adding to our pot preservation knowledge base is a new study from Italian scientists, who showed admirable restraint by using various methods to store various weed and hash for four years, in order to determine which was best for preserving the THC. As reported by Marijuana Moment, the scientists collected various high-potency hash and flower from law enforcement agencies, tested it for THC, CBD, and CBN, and then stored the weed in several ways: at room temperature, in a refrigerator, and in the freezer.
Per Marijuana Moment: "The testing conditions differed by light exposure (whether it was light or dark 24 hours) and storage temperature (including at room temperature, refrigerated at 4 degrees Celsius or frozen at -20 degrees Celsius). Over the span of the study period, the samples were tested 14 times."
The scientists discovered that the cannabis which was stored at room temperature, in both the light and dark conditions, had a reduction in THC by 13 percent (light) and 11 percent (dark). As THC denigrates, it converts into CBN, so those numbers went up as well.
The refrigerated cannabis showed a slower rate of THC loss, although after four years, what was stored at room temperature and in a refrigerator had lost nearly 100 percent of its THC. The cannabis which was stored in the freezer, however, retained virtually all of its THC, and experienced minimal degradation.
So if you have an extra pound you won't be blowing through anytime soon, the deep freeze is your best bet. Or, making some new friends and smoking it a bit faster works, too.