Know your Enemy: Light Leaks

Just wanted to make a quick post, hopefully it might help someone.

When starting to grow and looking at canna forums there is a lot of info to digest.

I've been growing for a while, and I just made a rookie mistake getting my new location up and running...

I didn't do a good job of checking for light leaks and I awoke to the unpleasant sight of MALE pollen sacs on my lovely ladies that were looking so good for 3 weeks into flowering!

So, just a heads up-THERE CAN BE NO LIGHT LEAKS WHAT SO EVER DURING THE DARK PERIOD OF 12/12. Even a pin hole size leak can ruin a crop.

If your growing in a tent or cab, it's crucial that you sit in your set up with lights off for at least 15 mins with bright lights put outside so your eyes can adjust to the dark and you can see ANY leaks. Any light leaks absolutely need to be fixed or you will run into problems with hermies or (if your lucky) slow bud development.

-Tents leak around zippers, velcro, and seams big time.

-Flexible ducting IS NOT light proof, so if any of it is exposed to light it will go right through it and into your tent/space.

-PASSIVE INTAKES are sketchy if your tent/room isn't in another completely dark room.

-If your cab or tent is in a room that is used while they are in their dark period, example your bedroom or basement rec-room, everything needs to be light proof including ducting and zippers. If need be make 'curtains' for your zippers using duct tape that is taped to itself, leaving a 1/2" of adhesive to cover your zippers when they are closed. I also recommend duct taping every seam in your tent wether you see a light leak or not.

-Don't forget under and around doors! Doors are not light proof.

-EXTENSION CORDS, SURGE PROTECTORS, HUMIDIFIERS, DEHUMIDIFIERS, AND EVEN FANS sometimes have little lights on them-if any of these things are in your space they need to be 'blacked out' with tape/black spray paint/etc.

Don't make the same mistake I just did! I know better and I still ended up have a light leak almost ruin my recent crop. I think it's something that is oftern over looked in the newbie forum but it's really important.

LIGHT LEAKS ES NO BUENO!

I've heard completely different. I'll try and find the thread but there are a good few growers who flip the lights on all the time to work on their plants not a green light and they have never have any problems. I'll go look.


https://www.rollitup.org/t/interrupting-12-12.831412/#post-10558298

Squidbilly said:

Even a pin hole size leak can ruin a crop.

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that's simply not true.

I'm one of the people that have light leaks lol. I'm not promoting it by any stretch lol. My shed consists of two rooms (sometimes) that is devided by silver bubble wrap. The bubble wrap is in it self light proof but the velcro does not allow for a perfect seal. Light does penetrate but not loads. Also I have left lights on by mistake (stoned) and open the door on occasion. I, in the last three years have never had a femmed seed throw balls. Perhaps I'm very lucky! Again just my experience, but could it be the ops seeds were prone genetically to throw balls?

Know your enemy: Spreaders of hogwash, poppycock, and just plain bullshit.

Light leaks don't cause plants to herm. A light leak (much larger than a pinhole lmao) can prevent onset of flowering and trick a flowering plant into re-vegging. But herms? No. Some nights I can see well enough to read a newspaper from the moon's reflection.

The rule of thumb is: nothing brighter than the light cast by a full moon. If plants in their natural environs have to flower under that bright light then gardeners can use that as a guide.

This debate looks interesting. I have just fixed up some leaks on my cab. I am mainly preping for smell but because I am lights out during the day in a shed with some sky light I am being cautious. All I know is:
Duct tape ain't lightproof, and
Keep it simple to avoid fixing heaps of lightly trouble spots after the fact.

maybe you had a bad batch of seeds, i have never known anyone to have that problem, the light would have to penetrate the mj, for example a cfl a foot away wouldnt emmit any lumens to the leaves, therefore it should in therory be safe to have light as bright as a cfl a foot away from the plant without having any issues, unless of course it ia a powerful light which can emmit project lumens to a greater distance, of course less is best but just for arguments sake i think it can be done, i am very interested to see, and soon i may conduct a experiment to test this therory.

UncleBuck said:

that's simply not true.

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Holy phuck, Uncle Buck and I agree on something. Sumbitch.

waterdawg said:

I'm one of the people that have light leaks lol. I'm not promoting it by any stretch lol. My shed consists of two rooms (sometimes) that is devided by silver bubble wrap. The bubble wrap is in it self light proof but the velcro does not allow for a perfect seal. Light does penetrate but not loads. Also I have left lights on by mistake (stoned) and open the door on occasion. I, in the last three years have never had a femmed seed throw balls. Perhaps I'm very lucky! Again just my experience, but could it be the ops seeds were prone genetically to throw balls?

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Yes, headband is VERY prone to doing that with very little stress/especially light leaks. I never had an issue with what you mentioned above, leaving lights on stoned-pin hole leaks-etc. It's why I made the post. I knew light leaks can cause hermies, but I never had an issue with it till now so I didn't tape every tiny little pin hole in my new tent, and I didn't realize how much light was getting in threw my flexible duct. The entire left side of my tent thew balls where most of the light was getting leaked in.

P.S - fixed all light leaks, removed all male parts, and so far so good. No signs of male parts in last couple days.

UncleBuck said:

that's simply not true.

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So hermies can't ruin a crop?

C'mon guys, this was for newer growers so they don't over look such a simple thing. It's hard enough for them to identify nanners or even realize what is going on before everything get's pollinated.

I'm sure you will see TONS of people who have had crops ruined by light leaks...I think everyone else just gets lucky/strain dependent.

Point is a light leak can be disasterous, so why risk it? It's never happend to me before, so I let my gaurd down.

I posted this is the newbie section, are we really going to tell them light during 12/12 is ok, or something that's not a big deal? I don't think that is helping anyone/is bad advice to be spreading.

I got light leaks thru zippers on my tent, never affected my crop, only plants that carry the hermie genetic will hermie due to stress. Think, in nature the moon shines, it casts a light, at night it isnt complete utter darkness.

Squidbilly said:

C'mon guys, this was for newer growers so they don't over look such a simple thing. It's hard enough for them to identify nanners or even realize what is going on before everything get's pollinated.

I'm sure you will see TONS of people who have had crops ruined by light leaks...I think everyone else just gets lucky/strain dependent.

Point is a light leak can be disasterous, so why risk it? It's never happend to me before, so I let my gaurd down.

I posted this is the newbie section, are we really going to tell them light during 12/12 is ok, or something that's not a big deal? I don't think that is helping anyone/is bad advice to be spreading.

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Agreed, light leaks arent really a good thing but saying that it will hermie ur plants and ruin ur crop isnt necessarily true, althought new growers should definitely keep an eye open cuz it can cause plants who have carried the hermie genetic to shoot nutsacks but with stable genetics that shouldnt be a problem.

UncleBuck said:

that's simply not true.

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Yes, utterly false even. Old hippie wives' tale...

dannyboy602 said:

The rule of thumb is: nothing brighter than the light cast by a full moon. If plants in their natural environs have to flower under that bright light then gardeners can use that as a guide.

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I tend to disagree with nearly any comparison to oudoors, indoor is all about controlling the environment and at the top of the list the light schedule, but I agree. Mind you though outside in the wild there tend to be more hermies, so ime this is not a very strong argument for the thick-headed hermafobists.

"As little as 0.03 footcandles (FC) [which is indeed the amount of light of a full moon] of red light interrupting the dark period will inhibit the anthesis of hemp. A long night thus becomes two short nights separated by an extremely short day, such as 1 minute of illumination."

Florigen (the various flower ho'mones) builds up during the dark period in the leaves of the entire plant. For a small light leak to cause problems it would have to lit most of the plant, which makes it no longer being a very small light leak, and is rarely the case with multiple layered canopy. Else florigen will continue to build up and 'win'.

Light leaks delay the transition and flowering, they do not necessarily cause hermies (an irregular light schedule is much more effective to create hermies).

Jussblaz3420 said:

I got light leaks thru zippers on my tent, never affected my crop, only plants that carry the hermie genetic will hermie due to stress. Think, in nature the moon shines, it casts a light, at night it isnt complete utter darkness.

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The moon, streetlights, headlights, home lights, business lights, billboards, runway lights...

If a plant hermies, it's not because of light leaks, it's because of shitty genetics.

I shouldn't of said hermies-if a plant is a hermie that is usually genetic.

If a plant throws nanners-that is stress related. Big difference between a plant being a true hermie and a plant trying to self pollinate itself due to stress, i.e. light leaks/etc.

And yes, were talking indoors which is completely different then outside.

I love canna forums- "it didn't happen to me so it's not true"-shiz that was my mentality until this episode.

There a many people running the exact same strain from the same breeder that aren't having issues, so I'm not going to think I'm the unlucky one to have 3 out of the 4 I popped(all on the same side of the tent) throw nanners. It was the light leaks disrupting their dark period and it stressed them into throwing nanners.

Wilksey said:

The moon, streetlights, headlights, home lights, business lights, billboards, runway lights...

If a plant hermies, it's not because of light leaks, it's because of shitty genetics.

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Didnt even think of headlights, street lights etc, i had a plant behind my house but cars pulling into my driveway and cars driving by on the street would shine lights on it and it never hermied

Squidbilly said:

I shouldn't of said hermies-if a plant is a hermie that is usually genetic.

If a plant throws nanners-that is stress related. Big difference between a plant being a true hermie and a plant trying to self pollinate itself due to stress, i.e. light leaks/etc.

And yes, were talking indoors which is completely different then outside.

I love canna forums- "it didn't happen to me so it's not true"-shiz that was my mentality until this episode.

There a many people running the exact same strain from the same breeder that aren't having issues, so I'm not going to think I'm the unlucky one to have 3 out of the 4 I popped(all on the same side of the tent) throw nanners. It was the light leaks disrupting their dark period and it stressed them into throwing nanners.

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Appreciate the info ur sharing cuz light leaks can be an issue so its wise to be careful but in the end i believe its all genetics man.

Never had a plant turn hermaphrodite on me. I suspect the nanners guys see that are normal in late flower confound them and they assume they've done something wrong. I've even had my timer go out, or wasn't using a timer and I plum forgot to turn the lights off, and I still only got a few bananas. And even still with several bananas I only found a few seeds. Ppl like finding seeds in my buds, it was like getting a prize in a Cracker Jack box, even though they won't get but watered down genetics they didn't know that.