A cannabis humidity pack is a two-way moisture controller you drop into a sealed jar with your flower. It holds relative humidity steady, usually at 58% or 62%, releasing water vapor when the jar runs dry and pulling it back in when things get damp. That keeps CBD flower from crumbling to dust and keeps mold from moving in. One 8-gram pack covers up to an ounce of flower in an airtight container, and it needs swapping every few weeks to a few months depending on how often you open the jar.
What a humidity pack actually does
The pack is a membrane wrapped around a saturated salt solution. That solution has a fixed equilibrium point, which is the number printed on the packet. In a closed jar, it releases or absorbs moisture until the air around it settles at that number. It is not a humidifier and it is not a desiccant. Think of it as a thermostat for water vapor.
Flower is hygroscopic, so this matters. Buds hand moisture to dry air until both settle somewhere in the low 40s, and at that point trichomes turn brittle and volatile terpenes leave the plant material faster. Push the other direction, into the high 60s, and you hand mold and mildew a place to live.
58% or 62%: picking a number
Most pack makers and growers land on one of those two figures. I reach for 62% when a jar has been sitting a while or when the bud showed up crunchy, because it keeps flower spongy and springy. 58% runs a touch drier, which suits people who grind and roll right away or who live somewhere swampy and worry about mold. Neither is wrong. Pick one and stay with it, since bouncing between numbers stresses the flower.
Below 55% is storage that is not working. Above 65% is a risk you do not need to take.
Sizing: how many packs per jar
Packs are sold by weight, and that weight tracks the volume of flower they can regulate. Rough guidance from the manufacturers:
- 4-gram pack: small jars, roughly a quarter to a half ounce of flower
- 8-gram pack: up to an ounce
- 62-gram pack: up to a pound
- 320-gram pack: bulk bins and larger totes
Two 8-gram packs in a quart jar holding an ounce works better than one. A dense, tightly packed jar needs more of them than a loose one, because the pack has to reach the air. Rest it on top of the flower rather than burying it at the bottom where airflow is poor.
Using them with CBD flower
- Move the flower into an airtight glass jar. A folded bag or a tin with a loose lid will not hold humidity, and no membrane fixes a bad seal.
- Drop the pack in on top of the buds and close the lid.
- Wait 24 to 48 hours before you judge the result. Give a bone-dry batch a full two days.
- Store the jar somewhere dark and cool. Heat drives terpenes off faster than dry air does.
- Take what you need, then close the jar again right away.
Opening the jar for an hour and then deciding the pack failed is the most common version of this mistake.
When a pack is spent
Boveda packs go stiff and crunchy as the solution dries out. Integra Boost ships with a card whose dot shifts color once the pack is done. Either way, a pack that no longer feels soft and pliable is no longer holding a number. In a jar you open twice a week, expect a few weeks to a couple of months. In a jar you rarely touch, six months or more.
Some people recharge spent packs in distilled water. It works for a while, but accuracy drifts and tap water leaves minerals behind in the membrane. For a few dollars, replacing the pack is simpler.
Common mistakes
- Leaving the jar on a sunny windowsill. Heat inside a sealed container is worse for flower than dry air.
- Forgetting the jar exists. Check every few weeks and swap packs as needed.
- Expecting the pack to cure flower. Curing happens before storage. A pack only holds the moisture you already have.
- Using one small pack in a large container and wondering why the number keeps drifting.
Get the seal right, get the size right, and a humidity pack is the cheapest way to protect the terpenes you paid for.