Short answer
Keep cannabis flower in an airtight glass container, in the dark, at 60 to 70 degrees Fahrenheit, with 58 to 62 percent relative humidity. Mold grows above 65 percent humidity. Light, heat, oxygen, and air movement break down THC, CBD, and terpenes. A sealed jar in a closet holds quality for 6 to 12 months.
Why storage conditions matter
THC oxidizes into CBN. Heat, light, and oxygen speed that reaction. UV light degrades cannabinoids on exposed flower in days. Terpenes are volatile. Myrcene boils at 334 degrees Fahrenheit, and other terpenes evaporate at lower temperatures. A jar left open loses aroma compounds in weeks. Trichomes are fragile. They hold most of the cannabinoids and terpenes, and they break off dry flower.
Cannabis Storage Techniques: Keep Flower and CBD Potent
Containers
- Amber or opaque glass jar with a gasket seal. Glass holds no static charge, so trichomes stay on the flower.
- Stainless steel or food-grade ceramic with a tight lid.
- Avoid sandwich bags and thin plastic. They are permeable to air and smell, and resin sticks to the walls.
- Vacuum-sealed bags for freezer storage.
- Child-resistant lids. Keep jars out of reach of children and pets.
Humidity
Target 55 to 62 percent relative humidity inside the container. Two-way humidity packs hold that range. Use 62 percent for flower you plan to smoke or vape, and 58 percent for dry herb vaporizers. Flower below 55 percent crumbles and sheds trichomes. Flower above 65 percent supports mold and mildew growth, and warm temperatures raise that risk.
best ways to keep cannabis fresh
Temperature and light
Store at 60 to 70 degrees Fahrenheit. Keep jars in a dark closet or cabinet, away from windows, stoves, and routers. A standard refrigerator runs at 35 to 38 degrees Fahrenheit, has high moisture, and carries food odors. A freezer works for storage of 1 year or longer, but only with vacuum sealing. Repeated thaw and refreeze cycles damage flower. Let frozen jars reach room temperature before opening them, so condensation forms on the outside and not on the flower.
How long flower keeps
- Sealed jar, dark, room temperature: 6 to 12 months
- Sealed jar, refrigerated: 6 months, with odor and moisture risk
- Vacuum sealed, frozen: 1 to 2 years
Terpenes fade before cannabinoids. Flower that smells weak may still test near its original THC or CBD level. Potency drops over time as THC converts to CBN.
Common mistakes
- Storing on a windowsill or in a bathroom
- Leaving the lid off between sessions
- Grinding flower before storage. Ground material has more surface area and oxidizes faster.
- Adding citrus peel, bread, or lettuce to add moisture. These bring mold and rot.
- Packing a jar tight with no air gap, which crushes trichomes
Labeling and legal notes
Write the strain name, harvest or purchase date, and the CBD or THC percentage on the jar. Hemp flower with 0.3 percent THC or less on a dry weight basis is legal at the federal level under the 2018 Farm Bill. State rules differ, and some states ban hemp flower sales. Check your state law before you buy or ship flower.