Effect of Altitude on Resin Yield/Quality

Some background:

My company has multiple facilities throughout the State, some are at sea level and some are at high elevation. We did a serious pheno hunt a few years ago at our altitude 5000ft facility and came up with a dozen strains that all yielded extremely well on solventless processing. 5-7+% yields on fresh frozen, great resin, full melt water hash.

We ran these same phenos at sea level, almost all but 2 yielded on average 0.5% less, many with significantly lower resin quality or worse melt attributes. Our team has been going crazy trying to figure out exactly why. We have a single cultivation manager overseeing both facilities and the quality of raw input appears to be very similar. He believes it is the same.

The cultivation is pointing fingers saying the extraction team is failing, while the extraction team thinks it could be the grow. I think it’s a bit of both, but what I do know is that the extraction team has done hundreds of extractions with genetics that were locally pheno hunted at sea level, gotten great yields, great melt. It has often been the genetics that we pheno hunted from high altitude that don’t live up to the hype.

My question:

Can anyone with more of a cultivation background point me in the direction of some literature about the effect of altitude on resin production and quality? My hypothesis is that even though we control temperature, humidity, CO2, lights, etc - the lower altitude is somehow creating either lower quality resin or different sized resin that our end product isn’t quite as good as our product made at 5500 ft. I could be completely wrong, but that seems to be the pattern. I just don’t quite understand why!


It generally been considered that higher resin production goes hand in hand with higher altitude. That is why the Himalayas are known for their excellent charas and the indica strain considered more resinous than the sativa due to it evolving at high altitude. This because it acts as protection against the sun’s rays which are stronger higher up in the mountains. The indicas thichomes glandular heads are also normally larger than sativas, which again leads to it being favored for hash production.


I believe your observations are caused by barometric pressure differences, which alter plant respiration and water use. I have observed exactly the same on well know elite clonal cultivars. Unfortunately the literature is a bit sparce here, such is the state of plant science. It makes me wonder how it works that some clones are passed around worldwide. Another well known drug plant, erothoxyllum spp., mostly won’t grow at altitudes less than 10000’.


Thanks guys, this is a great start!

I found this article (not necessarily cannabis related) but still gives some interesting information:

“Gale (1972b, 1973) predicted and demonstrated a potential increase of transpiration with altitude when there is less than the average lapse rate of ambient temperature (about 0.6 °C/100 m at mid-latitudes). This results from the higher total radiation absorbed by leaves, the increase in the diffusion coefficient of water vapour in air at reduced barometric pressure and the increased density gradient of H2O vapour from the leaf to the ambient air. This is contrary to the case of CO2 influx into leaves, where the two diffusion factors tend to cancel out (Gale, 1972a). Consequently, transpiration rates at high altitude may be very high, as for example in Mediterranean climates where temperature inversions are common (Cohen et al., 1981). Under such conditions and where water is available and stomata remain open, a 1000 m elevation above sea level may bring about a doubling of transpiration rates. von Caemmerer and Farquhar (1981) showed how vapour efflux through the stomata may impede CO2 diffusion influx and hence photosynthesis. Consequently, the effect of transpiration on photosynthesis should also be studied and included in the analysis of the effect of altitude on leaf gas exchange. Moreover, exposure to conditions that induce high rates of transpiration may exhaust available water. This results in closure of stomata and hence reduction in photosynthesis and may also bring about a more xeromorphic plant species composition (Cohen et al., 1981).”

My findings have shown that choosing indica strains over sativa ones will yield better hash overall. The info I outlined seems to be consensus in that regard, but if you want more scientific reasons for this your quest must go on.

It would make sense that transpiration would be affected by barometric pressure. Everything else is.

“The plant is able to reduce its transpiration rate because the cuticle (a waxy waterproof layer) protects most of its surface and the stomata are able to close up as the cells in the leaf start to lose their turgor (see leaf structure p117). The stomatal pore is bordered by two sausage-shaped guard cells, which have thick cell walls near to the pore. When the guard cells are fully turgid, the pressure of water on the thinner walls causes the cells to buckle and the pore to open. If the plant begins to lose more water, the guard cells lose their turgidity and the stomata close to prevent any further water loss. Stomata also close if carbon dioxide concentration in the air rises above optimum levels.”

Everything I have read so far makes me believe that higher altitude increases lowers barometric pressure, which increases plant transpiration. My expertise isn’t biology, so I’m still trying to come up with a reason why we might see slightly lower yields and a more waxy, lower grease, water hash at sea level versus altitude. All of this reading makes me think that the waxy cuticle would be more prevalent at higher altitude to prevent rapid transpiration… We are seeing a waxier, less greasy product at sea level.

It’s like a cartesian well, pressure differential moves the water. Lower pressure in the atmosphere means a lower condensation point, I believe, meaning more water available in the air to transpire.


So, how will the increase in transpiration affect resin yield/quality?

Transipiration is a big deal to plant life/health. Water has three vectors of entry into the plant, vs. 1 in the root system.

Look for a college textbook paired with a botany or biology 101, obviously botany would be more specific and useful in the long term. They are well illustrated and descriptive.

Does anyone have any definitive info on a particular temperature and/or come ppm that encouraged more trichs and terpenes? I’m am afficidanado of sorts, trying to hone my skills at growing at the moment, my rooms are getting into the 84-88f day and 74-77f nights…I run during the day with HID… I’m very interested if heat plays roll in robbing it of trichs…

Thanks ALL!!!

Transpiration is probably one part of the equation. But I do have this question: Are these grows both outdoor or both indoor? As someone else mentioned, UV rays are a little more intense at higher altitudes and this could be a factor. If they are both indoor grows then this wouldn’t be a factor.

Both indoor.

I keep reading the thread title as “Effect of Attitude on Resin Yield/Quality” :wink:

UV flux was my first response too…but

stopped my in my tracks. I would have made @Renchi’s argument, but supplemented with protecting DNA from UV damage being one of the primary reasons the resins exist.

When @puccinia suggested barometric pressure, it made sense, as that is another sensory input that could be tied to resin production in an evolutionarily relevant manner.

ie: knowing that you’re at high elevation, even if you currently don’t notice a high UV flux, it’s probably wise to turn up resin production, because the UV is coming…

as for the variants you’ve tapped into during your high altitude pheno-hunt that seem to give more/better resin at altitude, I would guess they are tied to the higher UV flux at higher altitudes, but are using barometric pressure or it’s effect on transpiration to “sense” their altitude.


Are uv bulbs good at small amounts to stress trichs out in indoor

I have 2 4ft double bulb HO pure uv fluro but I always been scared to use

Was told they need to be 3 ft above and highest I can get is 1.5-2.5ft, and if I didn’t get 3ft above they would burn… And to do like 4-15 min on per lights on?
Any thoughts

Thanks Cyclo! You always come through with an easy to understand/follow explanation. This makes a TON of sense and helps a lot with giving me focus on what to read in my botany books next.

1 Like

I chalk this up to be a Colorado grower myth. I can not find evidence of altitude affecting any portion of photosynthesis in a indoor setting. If you are in a sealed environment, the barometric pressure is based on your VPD, Temps, and amount of water being put into the room. If it isn’t a sealed environment, then the external environment is having play in the VPD, thus changing the rate of transpiration. If there is a case study that says other wise, Id love to see. I watched a Colorado Master Grower blame fried plants on altitude, instead of the 2500ppm slurry of bottled nutes he was feeding.In NC they are finding higher elevations causing THC spikes, which they are contributing to colder temps, and UV.

@Willbilly11 so you’re saying it’s an affect of attitude?



Altitudinal_Variation_In_Some_Phytochemical_Consti.pdf (1.4 MB)

Doesnt deal with cannabis but interesting nonetheless.