What is the best humidity for long-term cannabis storage?
62% relative humidity is the best humidity for long-term cannabis storage, with 58% to 62% RH as the safe working range. Pair it with 65 to 70°F (18 to 21°C), an airtight container, and total darkness. Flower stored above 65% RH invites mold, while flower below 55% RH dries out and loses terpenes.
Why 62% RH holds up for months
At 62% RH, cannabis keeps enough internal moisture to stay springy and enough dryness to stall microbial growth. Mold spores need water activity near 0.65 or higher to colonize, which sits close to 65% RH. Terpenes also escape faster in dry air, so a 62% pack protects flavor as much as texture.
Comparison: best humidity control options for long-term storage
Three setups cover almost every home stash. Each one holds the 58% to 62% window, and the differences come down to effort, size, and how often you replace the pack.
1. Boveda 62% two-way packs (top pick)
Boveda 62% is the simplest way to lock a jar at the target humidity. The pack adds or absorbs moisture until the air reaches 62%, so you do not chase readings with a hygrometer. Use one 8g pack per ounce in a quart jar, or a 58g pack for a half pound or larger container.
2. Integra Boost 62% (runner-up)
Integra Boost works on the same two-way principle and ships with a replacement indicator card. Performance tracks Boveda closely, though the packs run a bit drier in very large containers. Choose it if you want a visual cue for swap-out timing.
3. Hygrometer plus airtight jar (budget)
A calibrated hygrometer and a sealed glass jar cost less than a year of packs. This route needs weekly checks because humidity drifts with room temperature. Add a small humidity pack once readings fall under 58%.
How do you keep cannabis at 62% RH?
- Cure flower first, then move it to storage once stems snap instead of bend.
- Fill jars to about 75% capacity and leave a little headspace.
- Drop in a 62% pack and seal the lid.
- Store in a dark cabinet at 65 to 70°F.
- Open the jar for a few minutes once a week during the first month, then monthly.
- Replace packs when they turn rigid or flat, often every 2 to 4 months.
Is 55% or 69% RH better for long-term storage?
55% RH suits short sessions and dry herb vaporizers because the flower grinds finer. Long term, 55% RH bleeds terpenes and speeds oxidation. 69% RH feels sticky and weighs more at the scale, but it narrows the margin against mold. Stay at 62% when the jar will sit for months.
Does humidity matter for CBD flower?
Yes. CBD flower carries the same terpenes, trichomes, and mold risk as THC flower. The 58% to 62% window applies to both, and lab-tested hemp often arrives drier than expected. A 62% pack restores that moisture over 24 to 48 hours.
How long does cannabis stay good at 62% RH?
Sealed, dark, and held at 62% RH, cannabis keeps quality for 6 to 12 months and stays usable well past a year. Flavor fades before potency does. Rotate your stash and date each jar.