[ganjaments]

Is there any available data on how different (visible) light spectra affect THC Degradation (both pre and post harvest)? e.g. what is the best kind of light to use during and after harvest to minimize potency loss?

[Cannabologist]

- As far as I am aware, both exposure to air (oxygen), light (heat), and time in general will degrade THC to CBN.

-More exposure to more factors will hasten the conversion process.

- Environmental factors like light color can influence THC and cannabinoid production either positively or negatively during growth, though not by enormous amounts.

- THC and cannabinoid content is largely genetically controlled.

- Realistically, amounts of loss (conversion of THC to CBN) over time will be negligible.
*Example;
- Smoking 2 of the same sample side by side, you will not notice a difference in effect unless doing a comparison of fresh product to something years and years old.

-I have seen work done on the rate of conversion and will try to post a reference.

[MrBlue2]

Originally Posted by ganjaments

Is there any available data on how different (visible) light spectra affect THC Degradation (both pre and post harvest)? e.g. what is the best kind of light to use during and after harvest to minimize potency loss?

Its best to harvest your plants in the dark. Most of the starches in your plant will be in the roots during the dark cycle. if you harvest with the lights on the starches will be in the buds and leafs aiding in photosynthesis. this will result in harsher smoke.

Back to you question, UV light is the only type of light that i know of that will break down THC on living or chopped plants. Its pretty much always best to dry in the dark. dont worry about turning on the light in your drying room if its just a regular light bulb it wont mess anything up. Basically just dont dry your plants in sunlight or under a MH or anything crazy like that.

also the temp in your drying room should be between 65-75 degrees and the RH should be between 45-55%

[ganjaments]

Originally Posted by MrBlue2

Its best to harvest your plants in the dark. Most of the starches in your plant will be in the roots during the dark cycle. if you harvest with the lights on the starches will be in the buds and leafs aiding in photosynthesis. this will result in harsher smoke.

Do you have a link for this? It was my understanding that people harvest before lights on to obtain peak potency, before it has a chance to degrade from HID's?

Originally Posted by MrBlue2

Back to you question, UV light is the only type of light that i know of that will break down THC on living or chopped plants.

So a UV-Free lamp would be the best to use during and after harvest?

Originally Posted by MrBlue2

Its pretty much always best to dry in the dark. dont worry about turning on the light in your drying room if its just a regular light bulb it wont mess anything up. Basically just dont dry your plants in sunlight or under a MH or anything crazy like that.

Some people are pretty anal about light exposure (ever see a duct taped stash jar?), and having hard data on this would be quite helpful to quantify those concerns.

[MrBlue2]

Originally Posted by ganjaments

Do you have a link for this? It was my understanding that people harvest before lights on to obtain peak potency, before it has a chance to degrade from HID's?


So a UV-Free lamp would be the best to use during and after harvest?


Some people are pretty anal about light exposure (ever see a duct taped stash jar?), and having hard data on this would be quite helpful to quantify those concerns.

I use a green LED head lamp when i harvest. before i had a geen LED head lamp i just fumbled around in the dark. After I harvest I just have my regular house lights on (for hanging and later trimming). I always try to harvest right before the lights flip on or I flip the breaker on the subpanel to my room and leave it dark until i get around to harvesting. I know some growers who recommend 24 to 48 hours of uninterrupted darkness before harvest. I tried it and didn't think 48 hours of darkness was that much different then 10-14 hours of darkness. but if duck tape on your jars makes a difference to you then maybe the extra darkness will make a difference to you as well. I notice a difference in harshness in my smoke when i harvest with the lights on, there may be a difference in potency as well but i have never noticed it.


I think I read about the starches and harshness thing and the UV thing in Jorge Cervantes's grow bible or one of the ask ed books. Unfortunately I dont have either with me right now (and wont until after x-mass) so i cant be sure of which book or give you any direct quotes.

[Gooey]

thx for the info

[ganjaments]

MrBlue2 - Please don't take this the wrong way, but I am looking for actual data not anecdotal evidence. Why do you use a green LED instead of a UV-Free LED? Why do you then switch to regular house lights? What benefits is the 24-48h dark period supposed to give in relation to post-harvest potency loss? Do you have any data whatsoever showing a detectable difference using a Green, Red, Blue, UV-Free or any other light?

[MrBlue2]

Originally Posted by ganjaments

MrBlue2 - Please don't take this the wrong way, but I am looking for actual data not anecdotal evidence. Why do you use a green LED instead of a UV-Free LED? Why do you then switch to regular house lights? What benefits is the 24-48h dark period supposed to give in relation to post-harvest potency loss? Do you have any data whatsoever showing a detectable difference using a Green, Red, Blue, UV-Free or any other light?

I think the data your looking for doesn't exist. the question your asking is similar to, "how long does it take to get a sun burn?" I think if you do a little research on light you would find the answer your looking for. Green, Red, blue, and yellow light in there pure forms are all in the infrared spectrum. this means that they are all UV free. purple and violet light split the spectrum and have a little bit of UV light. the original meaning of ultra violet is beyond violet or everything darker then violet.

Prolonged exposure to HID lights, tanning bed lights, sun light, and UV lasers are the only sources of light that I know of that will degrade THC at a detectable rate. In other words, it makes no difference if you put duck tape on your jar, unless you leave your jar in a tanning bed or out in the sun for hours at a time.

I left out black lights from the list because they lack the intensity needed to cause damage in any reasonable amount of time.

If this answer isn't to your satisfaction, you could always do your own experiment. take five identical jars and put a gram of weed in each. Duck tape one and put it in a dark place as a control. Then put one of the remaining four jars in one of the following places. under an HID light, in direct sunlight, under a black light, and the last one should be placed in normal lighting conditions in your house. leave all of the jars in there places for the same amount of time (at least a couple of hours) then collect them all and put them in complete darkness until tested. If you want to be a little more accurate you could do twice as many jars and tape half to give you more controls and make sure other factors like heat aren't messing up your results.

also

as stated above a green LED is uv free. I use a green LED because the plants dont react to it and it will not interrupt their photo period.

and

I use house lights because those are the lights in my house. I think they are CFLs(the energy saver ones) or incandescents.

this too

You mentioned earlier that people harvest right before lights on because they want to chop before the HID lights begin to degrade the THC that has been forming overnight. This makes since to me. I was also under the impression that harvesting right before lights on will make your smoke less harsh. If one or both of these things are true then wouldn't it also make since to let the plants have a little extra darkness (24-48 hours), to let them make more THC and/or allow the starches to further evacuate the buds.

Peace, Mr. Blue

[ganjaments]

Originally Posted by MrBlue2

Prolonged exposure to HID lights, tanning bed lights, sun light, and UV lasers are the only sources of light that I know of that will degrade THC at a detectable rate.

Do you have a source for this, so that I may read more?

[El Toker]

I harvest when it's convenient for me to do so. That varies so can occur during lights on, lights off etc. I've noticed no difference potency as a result of this, and most of the time I tend to grow cuttings from the same plant for multiple grows.