Curing and storing cannabis

Curing lets moisture even out inside dried flower. Many growers prefer the aroma and handling that result, but a set number of weeks doesn’t guarantee better smoke or microbial safety.

Jar curing

1. Fill glass jars about three-quarters full and add a small hygrometer.
2. For the first week or two, open each jar for a few minutes a day.
3. If the settled jar humidity rises toward or above the mid-60s, the flower may need more drying. Check for spoilage before it goes back into storage. Opening the lid for a few minutes isn’t a dependable way to dry wet flower.
4. After a couple of weeks, open the jars less often. Many growers cure for 2 to 4 weeks or more.

Reading the jar

Jars or curing bags?

Clean, intact glass jars can be reused, but seals wear out and glass can break. Many growers open jars during early curing to keep an eye on conditions. Curing bags are lower fuss, but they only work if the flower is properly dry first.

Storing

For everyday storage, use clean, airtight containers in a cool, dark, stable place away from children and pets. If you refrigerate, keep the container sealed while it warms back to room temperature before opening, so less condensation forms on the cold flower. Avoid repeated warming and cooling.

In a controlled study, Milay and colleagues compared whole and ground flower of two chemovars in sealed bottles, all kept in darkness, at −80, −30, 4 and 25°C for up to a year. Whole flower at 4°C did best overall under those conditions. Terpenoids declined in every condition, and grinding and the deep-freezing treatments were unfavorable for preserving them. That doesn’t show every household refrigerator, or every freezing method, is better or worse.

At equilibrium and the same temperature, water activity roughly corresponds to headspace relative humidity divided by 100. A hobby jar hygrometer is only an estimate, not a calibrated aw test. ASTM’s 0.55–0.65 range doesn’t make existing mold or contamination disappear. Throw out suspicious material instead of trying to cure it clean.