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PL Sous vide decarboxylation runs at roughly 95C (203F) for 90 minutes to 2 hours, with the cannabis sealed in a food-safe vacuum bag or a lidded jar and held under water. At that temperature the rate measured in the laboratory converts about 95% of THCA in extract in roughly 75 minutes [1]; flower in a bag heats more slowly, hence the longer hold. The bath cannot rise above the boiling point of water, so scorching is not a risk.
What is sous vide decarboxylation?
It is decarboxylation done in a temperature-controlled water bath instead of an oven. An immersion circulator heats and stirs the water to hold a set point, and the sealed cannabis sits in that water until the acid form has converted.
The chemistry is identical to any other decarb: heat drives the carboxyl group off THCA, releasing carbon dioxide and leaving THC. How to decarb weed, the full decarboxylation guide, covers that reaction and compares every method. What changes here is the delivery of the heat, and that changes the numbers.
Two things follow from using water. The temperature is far steadier than an oven's, and it is capped. Both matter, and the cap is what makes the method slow.
What temperature and time does sous vide decarb need?
The times below come from one laboratory study that measured how fast THCA converts in cannabis extract at 80C and 95C [1]. The 85C, 90C and 100C rows are estimates calculated from those two measurements. Each suggested hold adds a margin for flower in a bag, which heats more slowly than extract.
| Bath temperature | Suggested hold | About 95% of THCA converted in extract | Notes |
|---|---|---|---|
| 85C (185F) | 3 to 4 hours | About 3 hours (estimate) | Slowest. Incomplete at the short end |
| 90C (194F) | 2 to 3 hours | About 2 hours (estimate) | A conservative middle |
| 95C (203F) | 90 minutes to 2 hours | About 75 minutes (from the measured rate) | The common setting |
| 100C (212F) | Not practical | About 50 minutes (estimate) | The water boils, so the circulator cannot hold the set point |
Not every source agrees. A review that fitted a trend line over earlier studies estimates about 3 hours for full conversion at 100C [6], much slower than the calculation above. That gap is one reason to stay at the long end of each range. The oven equivalents are in the decarboxylation temperature and time chart.
Times shorten with finer grind and thinner packing. A bag pressed flat to a single layer of ground flower reaches the bath temperature quickly. A dense wad in the corner of a bag takes much longer, and that time is not part of your hold.
Why can a water bath not go above 100C (212F)?
Water boils at 100C (212F) at sea level. Once it boils, added energy turns liquid into steam instead of raising the temperature. At altitude the ceiling is lower: the boiling point falls by just under 1F for every 500 feet of elevation, and at 7,500 feet water boils at about 198F (92C) [2]. Denver, at about 5,300 feet, caps near 202F (94C).
This is the single fact that shapes the whole method. It sets the top of the table above, it is why the hold times run in hours rather than the 40 to 50 minutes an oven needs, and it is also the method's main safety margin.
In earlier work cited by the same laboratory, CBN began to appear when pure THCA was heated to 160C (320F) [1]. A water bath cannot get within 60C of that. The failure mode of an oven decarb, walking away and coming back to a tray that has cooked past the target, is not available here. CBN and what it actually does covers that cannabinoid separately.
How does sous vide compare to an oven?
| Factor | Sous vide | Oven |
|---|---|---|
| Temperature control | Steady, stirred water at a set point, capped by boiling | The air cycles above and below the set point [7] |
| Time | 90 minutes to 4 hours | 40 to 50 minutes at 115C (239F) |
| Terpene retention | Expected to be better because the bag is sealed, but not measured in a controlled comparison | Volatiles leave with the heat [5] |
| Smell | Contained in the sealed bag until you open it | Strong, fills the house |
| Effort | Seal, set, walk away | Preheat, check with a thermometer, watch |
| Risk of overshoot | Effectively none, capped at 100C (212F) | Real, and the main cause of ruined batches |
| Equipment | Circulator plus a container. Vacuum sealer optional | An oven you already own |
The honest summary: sous vide trades time and equipment for control and smell containment. If you decarb once a year, the oven is the right tool. If you decarb often, live somewhere the smell is a problem, or have already ruined a batch by overshooting, the bath earns its place.
How do you actually do it, step by step?
What you need: an immersion circulator, a container deep enough to submerge the bag, food-safe vacuum bags that the maker rates for at least 100C (212F) or a heatproof glass jar with a lid, and a grinder.
1. Grind coarsely. Aim for the texture of coarse ground coffee. Powder packs dense and heats unevenly. Whole buds have cores that lag the bath.
2. Fill the bag or jar. Keep the bed thin. In a bag, press it flat to a single layer. In a jar, fill no more than half so heat reaches the middle.
3. Seal it. With a vacuum sealer, use the moist or gentle setting so you do not pull material into the seal. With a jar, close the lid fingertip tight and no tighter, so expanding air can escape rather than build pressure.
4. Use water displacement if you have no vacuum sealer. Take a zip-seal bag rated for the temperature. Close it to the last centimetre, lower it slowly into the water, and let the water push the air out through the gap. Seal it once the bag is submerged, and clip the top edge to the side of the container.
5. Set the bath. 95C (203F) is the default. Wait for it to reach temperature before the bag goes in, otherwise your hold starts from a number you did not choose.
6. Hold. 90 minutes to 2 hours at 95C (203F). Start counting when the bag is in and the bath has recovered its set point.
7. Cool. Lift the bag out and let it come to room temperature before opening. Opening a hot bag releases a concentrated burst of the smell you went to this trouble to contain.
8. Dry before infusion. Condensation collects inside the bag. Spread the material on a plate until it is dry to the touch. Water in your fat carries no cannabinoids and shortens the shelf life of the finished cannabutter or oil.
Then infuse as normal. Which oils work best for cannabis infusion covers the carrier, and once you have a weight and a starting percentage the potency calculator gives a per-portion figure.
What are the real limits of this method?
It is slower. Two hours against 40 to 50 minutes. If you are decarbing tonight for tonight, the oven wins on time.
It needs equipment. A circulator is a real purchase. Improvising with a pan on a hob gives you an oven's variance with a water bath's ceiling, which is the worst of both.
The terpene claim is not settled. Terpenes are volatile, and researchers keep the heating step short to limit their loss [5]. A sealed bag below boiling point should lose less, and home cooks often report it does. But no controlled published comparison of sous vide against oven decarb was found, so treat the advantage as an expectation, not a measured result.
On conversion itself: the maximum THCA to THC conversion is about 87.7% by mass. THCA weighs 358.5 g/mol and THC 314.5 g/mol, and the difference leaves as carbon dioxide [3][4]. No method beats that number, sous vide included.
If your edibles have been weak and you suspect the decarb step, why edibles do not work for some people covers the other candidates.
Frequently asked questions about sous vide decarb
Can you decarb in a jar without a vacuum sealer?
Yes. Use a heatproof glass jar, fill it no more than half, and close the lid fingertip tight so pressure can vent. Weight it down or it will float. Glass heats more slowly than a thin bag, so stay at the long end of the time range.
Can the bag melt in the water bath?
Not if it is rated for the temperature. Use bags whose maker states a rating of at least 100C (212F), which the bath cannot exceed. Do not use thin sandwich bags or any bag without a stated rating.
How long does sous vide decarb take at 95C (203F)?
90 minutes to 2 hours for coarsely ground flower in a thin layer. In extract, about 95% of THCA converts in roughly 75 minutes at that temperature [1].
Can you go above 100C (212F) in a water bath?
No, not in an open bath at sea level. Water boils at 100C (212F) and stops rising. At altitude the ceiling is lower [2].
Will sous vide degrade THC into CBN?
Very unlikely. CBN appeared when THCA was heated to 160C (320F) [1], far above anything a water bath can reach.
Is sous vide better than oven decarb?
It is steadier, smells less and cannot overshoot. It is slower and needs a circulator. For frequent decarbing it is the better tool; for once a year the oven is fine. If you are working out portions either way, the complete edible dosage guide is the next step.
Sources
- Wang M, Wang Y-H, Avula B, et al. Decarboxylation Study of Acidic Cannabinoids: A Novel Approach Using Ultra-High-Performance Supercritical Fluid Chromatography/Photodiode Array-Mass Spectrometry. Cannabis and Cannabinoid Research. 2016;1(1):262-271. doi:10.1089/can.2016.0020
- U.S. Department of Agriculture, Food Safety and Inspection Service. High Altitude Cooking. fsis.usda.gov
- PubChem. Tetrahydrocannabinolic acid, CID 98523. National Library of Medicine. pubchem.ncbi.nlm.nih.gov/compound/98523
- PubChem. Tetrahydrocannabinol, CID 16078. National Library of Medicine. pubchem.ncbi.nlm.nih.gov/compound/16078
- Boffa L, Binello A, Cravotto G. Efficient Capture of Cannabis Terpenes in Olive Oil during Microwave-Assisted Cannabinoid Decarboxylation. Molecules. 2024;29(4):899. doi:10.3390/molecules29040899
- Iffland K, Carus M, Grotenhermen F. Decarboxylation of Tetrahydrocannabinolic acid (THCA) to active THC. European Industrial Hemp Association / nova-Institut, 2016 (a review; its times are read from a trendline over earlier studies). PDF
- Sub-Zero Group (Wolf). Oven temperature issue. subzero-wolf.com
Equipment for decarboxylation and infusion at home: the NOIDS Basic Bundle.
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