Store cannabis flower in an airtight glass jar, in a dark cabinet, at 60 to 70 F and 55 to 62 percent relative humidity. Flower keeps usable potency for about 6 months with this setup and starts to fade after 12 months. Light, heat, air, and moisture are the four factors that break it down.
What causes potency loss
- Light: UV and visible light drive oxidation. THC converts to CBN, which is less intoxicating and more sedating.
- Heat: Decarboxylation and evaporation speed up as temperature rises. Terpenes are volatile and leave the flower at room temperature.
- Air: Oxygen reacts with cannabinoids and terpenes. Every jar opening swaps out the trapped air.
- Moisture: Flower above 65 percent relative humidity grows mold. Below 55 percent, trichomes dry out and break off.
Container choice
Glass with a clamp lid or a screw-top lid holds humidity best. Plastic tubs and zip bags let terpenes pass through, so the smell leaks and the flavor fades in weeks. Silicone absorbs terpenes and holds the odor. Vacuum-sealed bags work for long storage but can crush the flower when the seal pulls tight.
Keep the container full. Empty headspace is extra oxygen. If a jar sits half empty, move the flower to a smaller jar.
Humidity
Target 55 to 62 percent relative humidity. Two-way humidity packs hold that range: 62 percent for flower you will keep more than a month, 58 percent for flower you smoke daily. Mold needs water activity above 0.65, which sits near 65 percent relative humidity at room temperature. Do not add orange peel, bread, or lettuce to rehydrate flower. Those add moisture and sugar and give mold a head start.
Temperature
60 to 70 F is the working range. A closet shelf or a cool drawer works. Kitchens and bathrooms run warm and humid. Cars swing from hot to cold within hours. Above 77 F, terpenes evaporate and THC loss speeds up.
Fridge and freezer
A refrigerator cycles through temperature and humidity swings each time the door opens. The jar sweats on the inside, and that water lands on the flower. A freezer works for 6 months or longer if the flower is vacuum sealed and never thawed and refrozen. Let the sealed bag reach room temperature before you open it, or condensation forms on the trichomes.
How long flower lasts
With a jar, darkness, and humidity packs, flavor holds for 6 to 12 months. THC declines across that window as it oxidizes into CBN. Commercial packages carry a harvest or packaged-on date. Dispensary flower may already be several months past harvest before you buy it.
Signs of spoilage
- White fuzz, gray patches, or a web pattern: mold. Discard the whole container.
- Smell of ammonia, hay, or wet basement: microbial activity or anaerobic breakdown.
- Flower crumbles to dust when squeezed: too dry, trichomes lost.
- Brown color and no smell: oxidized, low potency.
Mold is not salvageable. Heat does not remove mold toxins.
Daily use setup
Keep a small jar for the week and a larger jar for the rest. Opening the main jar every day pulls in fresh air and shortens shelf life. Put one humidity pack in each jar.
Safety and labeling
Store flower where children and pets cannot reach it. Label each jar with the strain and the date you bought or harvested it. Keep jars away from household chemicals. In regulated US states, dispensary packages are child-resistant for this reason. A home jar with a clamp lid is not.