Lights Off....Strong Smell.

DesertGrow89 said:

Oh so it's due to respiration? I see

Click to expand...

I'm not sure it has been determined what is happening yet. Something occurs in the moments after the lights go out....there is too much empirical evidence to dispute that, but precisely what it is seems to be a bit of a mystery.

An interesting read.

http://www.realclearscience.com/journal_club/2015/06/29/why_some_flowers_only_smell_at_night.html

ricky1lung said:

An interesting read.

http://www.realclearscience.com/journal_club/2015/06/29/why_some_flowers_only_smell_at_night.html

Click to expand...

Interesting that you post that. In my search on this topic over the weekend I was reading about Lavender and how it needs to be planted on the West side of the house for it to be fragrant (in the afternoon sun) rather than on the East side (morning sun) because it just wont emit its fragrance much in the morning. It was a home and garden site and didn't get into any specifics other than "it just doesn't work".

Reading....

Total Head said:

i am familiar with the smell you're talking about, but mine isn't really a "lights off" smell. i noticed that my plants (regardless of strain) usually smell in cycles, and the smell is strongest about 2-3 days after a watering or feeding. the "plant" smell i notice more right after the plants are watered, and it's not the soil. the soil stops having a detectable smell after a couple weeks of use. a friend of mine noticed a long time ago that one day he would come over and claim i'm stinking up the neighborhood, and the next time he asks if i harvested already because the smell is gone. as far as whether this is good or bad or neither, i'm not sure.

Click to expand...

How often do u water and what kind of pot

It makes me laugh that my searching for why this happens led me here to a zombie thread.
I AM NOT SATISFIED, SOMEONE SCIENCE ME!
What I do know. It is some kind of respiration. All strains do this, some very strong. Its the same smell you get when you water them, but more intense. Very much a fresh cut grass smell (tempered by your strain). Even if I don't hear the click, I know within 2 min the light's has gone off in my closet. Smelled it for years. Not sure whats going on, but its why I never have a 24 hr cycle, even for cuttings.

I found a couple other threads here addressing same topic. More interesting, bit more info. would have posted there but....

Leef said:

It makes me laugh that my searching for why this happens led me here to a zombie thread.
I AM NOT SATISFIED, SOMEONE SCIENCE ME!
What I do know. It is some kind of respiration. All strains do this, some very strong. Its the same smell you get when you water them, but more intense. Very much a fresh cut grass smell (tempered by your strain). Even if I don't hear the click, I know within 2 min the light's has gone off in my closet. Smelled it for years. Not sure whats going on, but its why I never have a 24 hr cycle, even for cuttings.

Click to expand...

I asked the same question NINE YEARS AGO (https://www.420magazine.com/community/threads/smell-as-soon-as-lights-and-fans-go-off.144325/) and still have not received a satisfying answer from anybody so I will try to explain as best as I understand it from talking to a botanist and reading.

Plants undergo 2 phases of metabolism. During the light cycle they use light and chlorophyll to synthesize ATP, NADPH, O2 and an H+ gradient.

During the dark cycle (which can happen when the lights are on, it's called this because it doesn't require light) the plant takes in CO2 and uses the ATP, NADPH and H+ gradient to catalyze the synthesis of the sugars it needs to survive (this is called the Calvin cycle).

Plant's take in CO2, and expel O2 through pores on their leaves surfaces called stomata. In order to take in the CO2 to undergo Calvin cycle they must open up and when they do this some chlorophyll is offgassed partially catalyzed by the H+ gradient across the chloroplasts thylakoid membranes (partially because the stoma are open). It is suggested that the release is related to the amount of light the plant received before undergoing Calvin cycle which makes sense because the more light the stronger the H+ gradient and thus the more molecules of chlorophyll that can offgas


If this is incorrect uh ... you had 9 years to inform me so either shhhh ... or finally do it lol

Easy answer. Transpiration as well as respiration. Cannabis takes in o2 from the atmosphere and transpires terpenoids and c02 from roots into the atmosphere. Exactly the opposite functions during the day.
It's why grass at night many times after a hot, muggy day gives off that "cut grass" smell even though it hadn't been mowed.
Simple stuff really.

Is it Rh related