Curing
How to Burp Curing Jars: A Practical Schedule and the Gear That Helps
"Burping" is the simple habit of opening curing jars to let moisture and stale air out, then closing them again. It's the most active part of curing, and the part people most often get wrong, either by forgetting for days or by leaving jars open so long that material over-dries. This guide covers why burping matters, a commonly used schedule, how to read what your jars are telling you, and the inexpensive gear that takes the guessing out of it.
Quick answer
- What it is: briefly opening sealed curing jars to release moisture and refresh the air.
- Commonly used schedule: once or twice a day for a few minutes during the first week or two, then every few days, then about weekly.
- Let readings guide you: a small hygrometer in each jar tells you whether to burp longer, shorter or not at all.
- Red flags: condensation, ammonia or musty smells, or humidity that keeps climbing. Take material out and let it dry more.
Why burping matters
When material comes off the drying rack, the outside is often drier than the inside. Once sealed in a jar, moisture slowly migrates from the inside out and into the air in the jar. Humidity inside the jar rises. Burping lets that humid air out and fresh air in, so moisture can keep evening out without building up.
Skip burping during the early days and moisture can accumulate enough to cause off smells or mold. Burp too long or too often and you lose the slow, gradual finish that curing is for, and material can end up brittle.
Burping is part of post-harvest processing for many dried herbs and flowers, not just one crop. If you're curing cannabis, follow the laws where you live.
Before you start: is the material ready?
Burping can only manage a modest amount of moisture. It can't rescue material that was jarred far too early. A common readiness check is that small stems bend and then snap rather than folding limply, and the outside feels dry to the touch. That's a rule of thumb, not a guarantee; thick stems and dense material can be misleading.
If you aren't sure, jar a small test portion with a hygrometer and watch it overnight. If humidity climbs well above your target, the batch needs more drying time.
Setting up jars for easy burping
- Airtight jars with good seals. Glass is the most common choice. See glass vs plastic vs steel curing jars.
- Fill loosely. A commonly repeated guideline is to fill jars around three-quarters full without packing material down. Air space helps moisture even out and makes burping more effective.
- A small hygrometer in every jar (or at least in a representative few).
- Labels with the date jarred, so you know which schedule each jar is on.
- A cool, dark spot for the jars between burps.
- Enough jars. Overfilling to save jars makes curing harder. Our how many curing jars do I need guide helps you plan.
A commonly used burping schedule
There's no single correct schedule, and you'll see many variations. The table below reflects a pattern that's widely shared among home growers. Adjust based on what your hygrometers and your nose tell you.
| Stage | How often | How long open | What you're watching for |
|---|---|---|---|
| First few days | 1–2 times a day | Several minutes | Humidity rising quickly; any grassy or damp smell |
| Rest of first two weeks | About once a day | A few minutes | Readings settling into your target range |
| Weeks three and four | Every few days | A minute or two | Stable readings; aroma developing |
| After a month | About weekly, or as needed | Briefly | Anything unusual; otherwise mostly hands-off |
The jar humidity range most often quoted for curing sits roughly in the high 50s to mid 60s percent RH. Treat that as a commonly cited target, not a hard rule. If you use two-way humidity packs, our comparison of 62% vs 58% packs explains the difference between the two most common levels.
How to burp a jar, step by step
- Check the reading before opening. Note the jar's humidity on its hygrometer. This is the most useful number you'll get, because opening the jar changes it.
- Open and smell. Take the lid off and smell right away. You want the plant's normal aroma. Grassy means still moist; musty or ammonia-like is a warning sign.
- Gently move the material. Tilt or roll the jar so pieces shift and aren't pressing together. Don't shake hard or stir with your fingers; that breaks delicate material.
- Leave it open based on the reading. Higher readings get longer burps. If the jar is already in your target range, a brief burp is plenty.
- Close and label. Reseal firmly and jot the reading and date on a label or in a log.
Reading what your jars tell you
| What you notice | Likely meaning | What to do |
|---|---|---|
| Reading well above target that won't come down | Material went in too moist | Take it out and let it dry more on a rack or open tray before re-jarring |
| Condensation on the glass | Far too much moisture | Remove material immediately and dry further; inspect for mold |
| Slightly above target, slowly dropping | Normal early cure | Keep burping on schedule |
| In target range and stable | Cure progressing well | Reduce burping frequency |
| Below target, material crumbly | Over-dried | Stop burping; consider a two-way humidity pack |
| Musty or ammonia smell | Possible microbial growth | Inspect closely; discard anything with visible mold |
Why a hygrometer beats guessing
You can burp by feel and smell, and plenty of people do. But a small hygrometer in each jar turns curing from guesswork into a routine: high reading, longer burp; on target, brief burp. They're inexpensive, especially in multi-packs.
Budget hygrometers can drift or read a few points off out of the box. Calibrating them with a salt test or a calibration kit makes your readings meaningful. See how to calibrate a hygrometer.
Burping with humidity packs
Two-way humidity packs add or absorb moisture to hold a jar near a set level. They reduce how much burping you need once a cure is stable, but they're not a substitute for early burping. A pack can only handle small swings. If material is too wet, the pack becomes saturated and stops helping. A common approach is to burp without packs for the first week or two, then add a pack once readings settle.
Common burping mistakes
- Jarring too early and expecting burping to fix it.
- Packing jars full, leaving no air space for moisture to even out.
- Leaving jars open for hours, which over-dries material.
- Forgetting for days during the first week, the period when burping matters most. Set a phone reminder.
- Storing jars somewhere warm or bright between burps.
- Trusting an uncalibrated hygrometer that reads consistently high or low.
FAQ
How long should I burp curing jars each time?
Commonly a few minutes during the first couple of weeks, shorter as the cure stabilizes. Let your hygrometer guide you: higher readings call for longer burps.
When can I stop burping?
Once readings stay steady in your target range for a week or more, most people burp only occasionally. Many add a two-way humidity pack at that point.
What if I forgot to burp for a few days?
Open the jar, check the reading and smell. If it's high, burp longer or take material out to dry a bit. If you see or smell mold, discard affected material.
Do I need a hygrometer in every jar?
It's ideal, but not essential. At minimum, put one in a few representative jars from each batch, including the jar with the densest material.
The bottom line
Burping is simple: open, smell, check the reading, let the jar breathe for as long as the reading suggests, then close. Burp often in the first couple of weeks and less after that. A cheap hygrometer in each jar is the best upgrade you can make to the process.