Grow Talk

[CincyJay420]

So I’ve been thinking about the famous “60/60” rule — 60°F and 60% RH for drying and curing. Most of us have heard it a thousand times, and for good reason. That combo lands you at a VPD right around 0.7 kPa, which is basically the Goldilocks zone:

Slow enough to protect terpenes and cannabinoids

Fast enough to keep mold away

But here’s the thing… what happens when you can’t hit 60/60?

Maybe your space runs warm in the summer, or you’re drying in a basement that stays chilly. Do you just roll with it and hope for the best?

This is where understanding VPD changes the game.

VPD is all about the balance between temperature and humidity — the “thirst” of your air. If your temp changes, you can tweak your RH to keep the same drying speed as 60/60.

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Example:

Ideal: 60°F + 60% RH = ~0.7 kPa (perfect early-to-mid dry)

Too warm (70°F): Raise RH to ~68% → back to ~0.7 kPa

Too cool (55°F): Lower RH to ~54% → back to ~0.7 kPa

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Quick “VPD Rescue” Chart for ~0.7 kPa:

Temp °F Target RH %

55°F ~54%

60°F ~60%

65°F ~64%

70°F ~68%

75°F ~72%

(Close enough to keep you in the terp-preserving zone)

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Why it works:

Your plants don’t care if it’s 60°F or 75°F — they care about how quickly the water leaves their tissues. VPD measures that directly. If you keep the same VPD, you keep the same drying speed, and that means smoother smoke and better flavor every time.

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So here’s my question for the crew:

How many of you are actually watching VPD during dry and cure? Or do you just aim for 60/60 and call it good? I’m curious who’s actively adjusting RH to match their room temp, and if you’ve noticed a difference in your final product.

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Discussion

[Doja_Ridge]

I think you are right J. I’ve invested in tech for dialing in drying this year.

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[CincyJay420]

I cure in my basement, it stays right around 67° all year round. I am also in the Midwest (Ohio) where you could cut the humidity with a knife at times. I can leave my jar open several days and my buds still be squishy. I’ve learned to control humidty instead of temperature, as i can’t afford to keep the temps that low. My buds still come out stinky. Thus summer, during a heat wave (and while drying a crop) my ac went out. Temps upstairs reached 92°F inside. The basement was in the high 70’s. I was able to save the dry by pumping up the humidity to the mid 70’s, to keep the plant from drying out too fast, with minimal terpene loss.

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[sleep84]

I live in ohio too ugh

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[Doja_Ridge]

Tent drying Hydrone closed loop when i can and DIY cannatrol when I can’t.

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[CincyJay420]

Dude that is a beautiful set up. I am forced to pull my lights and use my tent to dry.

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[Doja_Ridge]

$125 to your door from ACI with pre order and DGC coupon code. DIY Cannatrol is $300 easy project. Even with a cup and a sponge 😉

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[justbe]

Are you referring to the wine fridge with an ink bird controller? I’m half temped to do this as there are wine fridges sold left and right for cheap around me.

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[Doja_Ridge]

Yes I Am

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[jmystro]

It took me many years of trial and error to come up with my drying SOP 30 years ago. I ruined so much flower those first 5 or so years before I figured it out. I’ve been sharing it with the DGC for the past 11 years. I still see it done half ass, thinking drying is a 2 week process. 60/60 is only half of it though.

Week 1-2: 60F/60%RH

Week 3: 60F/55%RH

Week 4: 60F/50%RH

Week 5: Remove ALL leaf and stem. Any hay smell is coming from leaf after drying is complete. Seal in container at 38-42F.

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[Newleaf]

“This is the way”!

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[Newleaf]

No for real DGC please take note! This process truley works. Ive been drying like this for 4 years thanks to this advice. I aslo try to spread this advice and i feel people either think its overkill or they just don’t have the patience for it. We put all this hard work into growing this plant. I see a lot of questions or posts that emphasize such concern about this deficiency or that small problem. I can see the care so many DGC put into their plants. PLEASE…finish this concern till the very end where it matters most. Give this method a true shot, and i promise you, you wont regret it.

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[CincyJay420]

@ jmystro I’m totally with you on your SOP — stepping RH down week by week is a rock-solid way to finish flower right. My post was more aimed at folks stuck on the warmer side who just can’t get their dry space down to 60°F no matter what. In those cases, adjusting RH to match the temp can keep VPD in check and protect most of the terps — I do get that some of the more volatile ones can start off-gassing at around 70°F — but you can still keep the overall profile and smoothness pretty dialed in, even if temps are higher than ideal.

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[jmystro]

Relative humidity determines how much moisture a flower can hold, while temperature determines how fast the flower can get to that moisture content. Heat is the enemy because it speeds up a process you want slowed down. Temperature also affects the chemistry in the trichome. I want the flower as cold as possible without freezing for as long as possible with little handling. My flower has no smell in the drying room because it’s too cold. Only a handful of terpenes can off gas through an oxidized cuticle anyway.

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[daxg]

Some arent able to get down to 60 degrees fahrenheit especially in the desert. I find 68 to 70 is great for finishing if you have a solid RH around 50 to 55 percent.

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[CincyJay420]

You should be raising humidity when you can’t lower temps to stay in that 0.7 kpa , to keep the dry slow. Lower humidity and higher temps will cause the plant to dry too quickly.

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[daxg]

I live in a very hot dry area so sometimes this difficult as well but ive always had great results as long as i jar them for a full two weeks burping 1 time a day

• This reply was modified 4 months ago by  daxg.

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[daxg]

Around .9 kpa

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[waynerigsby82]

Southeast Ohio here….

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[CincyJay420]

What part? Obviously i am in Cincinnati.

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