Lighting regimen

[Munkey]

Hello All,

I have seedlings that are coming up on around 2 weeks old and are going gangbusters. I am running a 600W LED in a 3x3 tent currently on the 18/6 schedule. My question is what, if any, would be the consequences of switching to a 24/0 regimen?Any and all input is much appreciated.

[DrPhoton]

Not sure if your asking about the stress from moving from one light schedule to another or asking about the differences between light cycles. If the first, it should be fine not much stress involved. If the second, i would direct you to my "Light Cycle Debate" article. Any further questions just ask.

[Munkey]

Thank you for your input. I should have clarified. I am growing photoperiod and was curious if there would be any undue stress put on them if I increased the lighting to 24/0.

[DoctorJohnson]

Assuming that you are at 18/0 now, I would expect that you would just see increased growth.
Folklore is that plants need "sleep," but I have vegged at 24/0 with a time lapse camera running the whole time and seen continuous growth.

[Campesino]

You'd get slightly faster growth, but you get diminishing returns so you spend 25% more electricity, but certainly don't get 25% more growth.
If after two weeks at 18/6 they are growing like "gangbusters" then you should probably leave well enough alone.
If you are growing Photoperiod Plants, I would avoid increasing light duration within a few weeks of flipping to 12/12.
If you are growing Autos, there are fewer reasons not to increase to 24/0, and would based more on whether you want to maximize yield (24/0) or efficiency (18/6)

[DrPhoton]

DANGERDAN LIKES THIS ^.^

It does appear that going beyond 18 hours does not return with linear gains.

[Campesino]

Thanks DrPhoton
I have certainly expanded my knowledge of lighting from your articles and our discussions.

[DrPhoton]

👍 Glad to hear it, im actually taking a break from writing for a while. I have some good topics to write about, but nothing was really flowing on paper. So i figure i have writers block ^.^

Im just gonna enjoy some grows for a bit.

[DoctorJohnson]

DD and Campesino, not to be argumentative, but do either of you have actual experience with 24/0 or are you simply repeating what you've heard?
I kept a time lapse camera on a plant under 24/0 illumination for weeks and growth was fast and steady throughout. I would say that I did get 25% more growth.
With an auto under 24/0 from seed to harvest, I got amazing results, much better than I got with less aggressive lighting schedules.
I'm not saying that you're wrong, necessarily, but saying "it does appear" and you "certainly don't" without actual experience kinda sounds like armchair quarter-backing to me. No disrespect intended...
I'm really not looking for a fight. Do what works for you...

[Campesino]

I actually do use 24/0 for seedlings and early veg under CFL with photoperiod plants. If I were ever to grow Autos I think I would probably run them 24/0, but I'd need to turn the light off to water and train so maybe 23/1.
So, I guess I don't really think our opinions on lighting differ that much.
Read DrPhoton 's articles if you want additional lighting citations
And a person that doesn't want to fight refrains from calling names.

[DrPhoton]

I look at the science and research has shown that plants can respond negatively or positively with continuous lighting. There is a good paper that reviews all the current research on the subject and provides pretty good clues as to the reasons why this multiple response occurs. So its not exactly a clear cut answer and is dependant on the type of plant. There is also no conclusive answer for cannabis as well, so we can only go by what people say. Although there is still an increase in growth with continuous lighting, there does not appear to be a universal agreement that continous lighting is linear with what is gained for a given amount of energy. The best way to tell if continuous lighting is effective, is by weighing the difference in a side by side or by assessing the amount of time the vegetation stage is shortened. Using vegetation time, people have reported mixed results. Some saying it only shortened a few days, some saying more. Nebula also believes that continous lighting does not seem to provide the most efficient return.

As i had previously said it "appears" to not provide efficient returns for a given amount of energy. If the experiences were more universal and consistant towards continous lighting i would be more confident, however results seem to vary widely. What i do know for a fact is that some types of plants respond negatively (tomatoes for example) to continous lighting. So there is the potential for this to be the case for cannabis as well. I feel it is much safer to have a light cycle with some amount of dark, as the downsides of such is small compared to the potential risks of continous lighting.

But im open to discussion, feel free to offer any further information you may have. What i would like to know is what the majority of the commercial indoor growers use. I know a couple still use 18/6.

[Locrian99]

My current grow I ran my vege 24/0 until about 2 weeks before the flip to 12/12. Then I switched to 18/6, figured it would be less stressful on the plants. Made sense in my head was the only reason for this logic. My completely not scientific observation was 24/0 didn’t really seem to have much of a benefit in the growth rate vs 18/6. Of course since I topped and transplanted during the time they were in 24/0 I would expect a little less growth from stress etc. just my experience...

[KingKush]

Hmmm I only bloom for 10/14 and it works fine for me.
OP never mentioned autoflowers so assuming photoperiod strains, keep the veg to 18/6 for maximum SUCCESS (for the grower). It's easier when your plants are not stressed out all the time and continuous lighting will be a bigger challenge than light cycles especially for novices.



This thread needed some pictures lol

[DoctorJohnson]

> And a person that doesn't want to fight refrains from calling names.
You're right. I apologize for that.

[Chefbjy]

I have had a little experience going from 18/6 to 24/0. A lot of plants differ and sometimes you can benefit with added light hours. Not all plants will react the same and I've had no problems switching the schedule to increase light hours. It negatively impacts your electrical bill and you'll have to decide what's best. If there's enough growth with the extra hours to warrant the use of 24/0 light go for it. I know most of my plants did best under 18/6. However when I took clones and did mainlines on them they responded to 24/0 light in a great way. With enough growth during the added light hours for me to continue using 24/0 till a week before flip to 12/12. Not all plants will react the same and most plants respond best to 18/6. I've not grown autos but I'd probably run a24/0 light sched with them if I did just to see if it was feasible. Give it a shot for a week or 2 and see for yourself if there's enough growth to continue. Without time to rest though/dark times your plants become more susceptible to stress and deficiencies or problems. There's a good article on light scedules on gwe main site and DANGERDAN has very informative articles on the subjects.

[Munkey]

Thank you everyone for your input. 20 heads are better than one, no pun intended. 😬