Lights on during flowering hermie myth?

Hi everyone!

So this is something I have heard hundreds of times : "any light in the dark period during flower will cause hermies and will stop it from flowering".

Now I have been growing for over 5 years indoors and I atleast once per week clean everything up during the dark period by opening up the tent letting light in...



My plants always flower no problems and stay females.. No hermies...


I think it's a myth that "one second of light ruins it"

I have left the tent open for hours with no response from the plant...it carried on flowering perfectly...


Thoughts?

I don't think it's completely a myth that light during the dark period can cause hermies, but I do think it's highly (read: incredibly) overstated. I too have worked in the room with lights during the dark period, as well as having dim diffuse light leaks through venting, and haven't had any issues. I have heard people claim a single dim 3mm indicator led on a humidifier or other device can cause an entire 4x4 tent to go hermie, which I think is utter bullshit.

I do think that if you have consistent interruption every night you will have problems, but I don't think the occasional working with lights on or having light leaks of a few lumens has much impact. I think a lot of it stems from bad genetics already prone to hermie, or plants that have already been under considerable stress, with a light leak or interruption serving as the catalyst to trigger plants to go hermie.

Just my 0.02c, and I generally still avoid any interruption at night if possible.

I've read that if stress techniques were used to create the seedstock, those seedlings may be
predisposed to sexual confusion in the down line. Considering we may have no idea of the generations of abuse before we got the seeds...I'd say its risky foolish to purposely interrupt a flowering cycle.

I agree... It's genetics not really the "light leaks"

chemphlegm said:

I've read that if stress techniques were used to create the seedstock, those seedlings may be
predisposed to sexual confusion in the down line. Considering we may have no idea of the generations of abuse before we got the seeds...I'd say its risky foolish to purposely interrupt a flowering cycle.

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I agree that it is not wise to intentionally interrupt the dark period, but I also think there is little risk in turning the lights on if you absolutely have to, as long as it is not done all the time.

I have a clip on light, green of course, because plants supposedly dont see that color. I used to clip it on my shirt. Then I put a green cfl in the room on a switch, used that switch twice in 7 years.
I used to use the green light often when I grew in hydro. but now since its all soil/organic equipment stopped calling me during
lights out.

Sureshot2 said:

I agree that it is not wise to intentionally interrupt the dark period, but I also think there is little risk in turning the lights on if you absolutely have to, as long as it is not done all the time.

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well, if you have 20, 30 , 50 plants at different stages in a perpetual system....flicking lights on and off is risking 10's of thousands of dollars with every flick. seems silly to me, but the risk is subjective of course.

"Oh heck, I only have one plant in there, I aint risking anything so Ima gonna take chances and dare that girl to fail, may as well....."

it really is easy as pie to schedule work at lights on, or the other way around, even.

Myth is more like it!

I have yet to have any problem from a light exposure during bloom. Same thing noticed by all my friends growing around the same length of time......no herming.

I have a spot I did an outdoor for years. Few years back I put up a big cfl flood by the back deck. It hit that plant space pretty hard. About 14 ft high and 16 ft away.
The first year it was up, I saw in bloom that the side to the light. Was running about 10 days behind the "dark side" of the plant. It never had any herm issue....I simply harvested the dark side first. 2 weeks later, the front side.

To put a guess as to where that came from. I'll bet dimes to dollars, that was one of the first reasons growers of note thought that the herming problems from the old early "FEM SEEDS" days. Used to explain why those seeds hermed so much..

My herms came from poor genetics brought on by heat stress. Never had an issue with light leaks causing hermies. I had a lot of light leaks when I first started growing. After about 6 years of growing I did encounter a seeded plant / crop due to the sketchy genetics but it was brought on by environment.

Light leaks can lead to "reveg" or hermaphrodite "bananas", but that is directly related to the severity of the "leak", the plants genetics, overall health, exposure to other stressors, etc.

I'll say this...

It isn't the extreme outcomes that you should be concerned with, these rarely occur. The effects of subtle changes, minor details, are significantly more important. Considering the topic, the plants may not go full blown hermie/reveg with some exposure to light during "lights out", but that does not mean that there isn't any detriment. One
Chili cheeseburger won't cause a heart attack, but many over time... Minute exposure to radiation may not cause cancer, but over time... A minor nutrient imbalance may not cause "burn"/lockout, but let that imbalance build over time... Anything that detracts from optimal has a negative effect on your final product, drastic or minuscule. Stressors, at any level, do not go without consequence. Treat them like Olympic athletes (the ones that don't use "gear"), or a fine tuned machine.

My plants are expensive to grow and process, patients count on my success. I've never let them down to date. I grow really good cannabis. I followed some grow rules early on and they never failed me. Set it and forget it for me.
Why take the light leak chance is where I'm coming from, with so many grow fail factors I figure why add another one, especially one so popularly toted by light leakers already.

The healthier and happier the plant the less anything bothers them.

I've left the window on my tent open a few times, with a t8 shop light right over it, going for hours after the tents lights are out. I've never had issues. Then there's usually a small opening where my wires go in the tent that let's some light in. I've always thought it was more about light intensity/ consistency. If the plants are used to low level lighting all the time, they won't be effected, or not as much, as plants that are used to a completely dark period then hit with random light 4 weeks in. There's some post around here where people talk about the minimum needed light exposure in order to somehow neutralize the flowering hormone, hormones? Basically says the little indicator lights on powerstrips/fans/etc ands minor light leaks aren't powerful enough to cause any issues.

I'd be willing to bet there a combination of environmental factors going on in those cases, forcing the plant into last ditch survival mode.

There are chemical reactions that only happen during the dark period. Messing with those reactions by turning on lights is not a good idea.

Odin* said:

Light leaks can lead to "reveg" or hermaphrodite "bananas", but that is directly related to the severity of the "leak", the plants genetics, overall health, exposure to other stressors, etc.

I'll say this...

It isn't the extreme outcomes that you should be concerned with, these rarely occur. The effects of subtle changes, minor details, are significantly more important. Considering the topic, the plants may not go full blown hermie/reveg with some exposure to light during "lights out", but that does not mean that there isn't any detriment. One
Chili cheeseburger won't cause a heart attack, but many over time... Minute exposure to radiation may not cause cancer, but over time... A minor nutrient imbalance may not cause "burn"/lockout, but let that imbalance build over time... Anything that detracts from optimal has a negative effect on your final product, drastic or minuscule. Stressors, at any level, do not go without consequence. Treat them like Olympic athletes (the ones that don't use "gear"), or a fine tuned machine.

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That is quite correct Odin! (I forgot about multiple source stress) Every time I have ever seen any herm (bisexual) problem arise. Has been from multiple stress sources, all coming together close to each other, to all at once...

The last under my lights was an old strain from the stress induced S1 days.. That one was all genetic. The purchased seeds were like 50/50 in herming or not. Stress the "nots" and they hermed too. Sad part was I liked the finished product....way it goes sometimes!

My neighbor had a problem with one strain that popped nanner's after an 18 hr power outage. He also had high N/P problems (That I could see) along with cold stress from the heat not running = his root ball went to around the low 40's - high 30's..

I just had a timer failure in a bloom room. Fucking light stuck on for 2 1/2 days, till I went in before "on" times and found it....Plants were in differing points in bloom. So far only a slow down with minor FTing on the ones closest to finish....No problems and no nanner's...Days out as the ambering is begining.....Sucks though.....I see them as not being perfect to the strain. Others don't see it at all...

Point is, no nanners but like you said, "change".

My "Mystery" is a finicky gal. I altered the light cycle mid bloom and she threw bananas everywhere, seeded the entire room. I kept some (maybe 2k), never popped any of those. The only other time I've seen stressed induced bananas (in my gardens) was in the HPK (one branch of one plant) after the CO2 reg busted and dumped a couple tanks into the room.

Interesting on the Co2 issue....

Odin* said:

My "Mystery" is a finicky gal. I altered the light cycle mid bloom and she threw bananas everywhere, seeded the entire room. I kept some (maybe 2k), never popped any of those. The only other time I've seen stressed induced bananas (in my gardens) was in the HPK (one branch of one plant) after the CO2 reg busted and dumped a couple tanks into the room.

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what would "two tanks" dumped read on your meter in your room ?

@chemphlegm That meter maxed out at "5,000", the "2 tanks" would have been approximately 150,000ppm. They were full, connected both that evening before I left, regulator "flow meter" degradation led to disaster.

I wondered because a buddy put a few mature plants in a big plastic bag, vacuum'd the air out and cracked the valve on the c02.
I watched his mites die, his meter topped at 10k. A few hours later we got back, squirted them with a water hose and they were fine finisher/no issues over the next four weeks