Harvest time question

[scottmason]

I am on my 3rd grow now every thing has been going great, I've got one question that I can't find a answer to... should you harvest during the dark cycle or after the lights have been on for awhile? Thank you for all your help

 

[Carmen Ray]

HI Scottmason, welcome.
You might get a bunch of answers to this question. Personally I just harvest when I am happy with the trichomes and at a time of day that is convenient for me.
Happy growing!

 

[Bill284]

Welcome to 420Magazine my friend
For maximum tric production 36 hrs of darkness before harvest is standard practice.
LED lights degrade trics.
So after 12 hrs of light they shrink.
Giving them 36 hrs of darkness makes them swell.
How are the ladies doing?
All the white pistils gone?
Is she still draining her pot regularly?
Any pics?


Stay safe
Bill284

 

[Tokin Roll]

Welcome to 420 Magazine @scottmason

What type of growing do you enjoy?
Do you have any images you would like to share?

To answer your question: some like to put their plants in a 24-36 hour dark period after the trichomes have developed.

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Stay safe, and grow well my friend,

Tok..

Also, we now have a Fungi section if you would like to grow mushrooms.

 

[Delps8]

That's a not uncommon "truth" for some cannabis growers and I would love to see any actually data to support it.

 

[scottmason]

This is my 3rd grow, still have a lot to learn, but love it, waited many years to be able to grow. I am 55 and from OHighO

 

[Phytoplankton]

That's a not uncommon "truth" for some cannabis growers and I would love to see any actually data to support it.

They actually have done some studies, what was found is that it is best to harvest after a dark period for optimum terpenes, since the terps degrade in heat/light. It doesn't affect THC content one way or another, but there are increased terpenes at the end of a dark period.

 

[Bill284]

This is my 3rd grow, still have a lot to learn, but love it, waited many years to be able to grow. I am 55 and from OHighO

You may have just learned but it looks like your an old pro.
Absolutely Stunning lady.
Lights out 36 hrs before chop for max terpines.
Nice work.


Stay safe
Bill284

 

[scottmason]

Hi Scottmason, welcome. I answered your question in your other thread. You have created two threads by mistake

Thank you for your help. Sorry about the repost.. first time posting

 

[scottmason]

They actually have done some studies, what was found is that it is best to harvest after a dark period for optimum terpenes, since the terps degrade in heat/light. It doesn't affect THC content one way or another, but there are increased terpenes at the end of a dark period.

In turn...if Iam right should help the flavor??

 

[Bill284]

In turn...if Iam right should help the flavor??

Increased turpines will improve flavor, absolutely



Stay safe
Bill284

 

[Delps8]

They actually have done some studies, what was found is that it is best to harvest after a dark period for optimum terpenes, since the terps degrade in heat/light. It doesn't affect THC content one way or another, but there are increased terpenes at the end of a dark period.

If you can post links to the research, that would be great.

 

[Phytoplankton]

I”ve looked, and will keep looking, I thought it was by buggy or Rosenthal. Bottom line was at the end of a dark period, didn’t have to be over 24 hours, there were more terpenes than at the end of a light cycle. As I recall it was about 2-5% higher.

 

[KeyFinger]

I am on my 3rd grow now every thing has been going great, I've got one question that I can't find a answer to... should you harvest during the dark cycle or after the lights have been on for awhile? Thank you for all your help

does not matter actually, but I do it with the lights one and once trichomes are milky

 

[Delps8]

I”ve looked, and will keep looking, I thought it was by buggy or Rosenthal. Bottom line was at the end of a dark period, didn’t have to be over 24 hours, there were more terpenes than at the end of a light cycle. As I recall it was about 2-5% higher.

Bugbee did the "huh?" when asked about this but is Rosenthal a researcher or a grower+author. I ask because there could be multiple factors in play and the original research documents can be very helpful.

When lights aren't turned on for 36 hours, darkness ensues (cue "The Thriller") but at least two other parts of the grow environment are markedly impacted - temperature and humidity.

So "turn off the lights 36 hours before harvest" results in photosynthesis going to zero, temperature dropping, and RH increasing ('m "thinking out loud" here). I stipulate that all of those happen but it's not because of shutting off the light but the results of shutting of the light (secondary impact).

What this ties back to, for me, is two videos by Mitch Westmoreland, one from 3± years ago about his work with "hemp" and the other being the two videos that he did this Spring in which he shared his some of the research that's he's doing for his PhD (I want to type "pHD"!). Westmoreland is a doctoral candidate under Bruce Bugbee.

The issue is that in his hemp video he said that secondly metabolite levels plummeted/dropped/were dramatically reduced at canopy temps >78°. I didn't pay all that much attention to it but, fast forward to this year, and he lays down the hammer in both of his YT videos. They're a gold mine for growers, BTW.

His research shows that flower temps over 78°…"sacrifice" secondary metabolites. I won't use "devastate" but that's pretty much what he discusses.

His advice is to keep ambient temps high (up to the mid-80's) until the second week of flower because that will maximize vegetative growth, giving you a large plant with lots of branches and leaves, but, after the second week of flower, drop your ambient temp so that a the tops of the flowers are <=78°. He states that 78 is the highest temp you should have in flower and that some strains benefit from even lower temps.

When I read that, the light went on for me because I've done my grows with temps up to the mid-80's and yields have been significant but the kick hasn't been as much as I've experienced with the top shelf cannabis from a dispensary. Putting adding 2+2, my suspicion is that, even though my temps in flower are just over 80, the flower tops were hotter and that might have pooched my THC + terpenes.

That's why the idea of shutting out the lights is intriguing but it might be that the drop in temperature is what is making the growers get a crop with a better kick but, not being able to do the research in a lab, growers conclude that it's shutting off the light.

Caveat - as I've asserted, "shutting off the light" results in darkness, cooler temps, and > RH but I'm adding the above because I'm trying to get to which change in the grow environment causes the change (change in PPFD, temperature, and RH) vs what the grower did that caused the change (shutting off the light).

I'm voting with my wallet on this.

I'm retiring my Growcraft X3 (330 watt) flower light and replacing it with a Vipar SE4500 (430 watts). That's for a 2' x 4' tent and, according to Vipar, it generates over 1200µmol at 16" and 1000± at the edges. My thinking is that I'll be able to use a hang height of 18" and still get 1kµmol on the canopy and, by raising the light that high, I'll keep the temp down.

Additional point - for my Spring grow this year, tent temps were hitting the mid-80's on some days so I switched from the driver in the tent to the driver outside the tent (I have a 330 watt veg light and a 330 watt flower light so I can swap the cable easily). The driver in the tent was at least a foot above the light which was 12"-14" above the canopy.

I was expecting that the temp at the canopy would drop by switching to the driver outside the tent. Nope. I checked canopy temp before and after swapping and, even though the max temp of the light bars was barely over 100°, that was enough to heat up the canopy by mid-afternoon each day.

I add that because I'd always thought that moving the driver out of the tent was the way to keep temps down but, at least in my situation, the bigger issue is the light bars.

I'm adding this in the interest of discussion and to share news about some really interesting research on cannabis. I won't be starting a grow until things cool off in September or October but the light was on sale ($315 for a 430 watt light!) and I think the info from Westmoreland is worth sharing.

Thoughts and comments welcomed.