Do plants benefit from a dark cycle?

[Blunted22]

Im sure they do... just wondering if having my lights on 24 hours too try and make them veg faster would be counterproductive because they dont have a dark peroid.... i leave my clones on my e z cloner for month sometimes... so i guess it cant be too bad...

18/6 is the dark cycle normally used.... does it make a diff if you use a longer light cycle with a shorter dark cycle? 20/4

thanks for the input in advance....

 

[drtask]

i recently ran an expirement and really liked 20/4. i'm going to try something new this run. start at 18/6 for the first month of veg then into 20/4 for the second and then into 12/12 for flower. see how things go. but think of it kinda how humans grow. during the sleep period is when most growth happens. so i'd say a dark period definitely benefits plants as well.

 

[Hydro-Soil]

Im sure they do... just wondering if having my lights on 24 hours too try and make them veg faster would be counterproductive because they dont have a dark peroid.... i leave my clones on my e z cloner for month sometimes... so i guess it cant be too bad...

18/6 is the dark cycle normally used.... does it make a diff if you use a longer light cycle with a shorter dark cycle? 20/4

thanks for the input in advance....

Cannabis is of a plant type that doesn't 'Require' a dark cycle for complete growth. For indoor growers, leaving the lights on 24/0 during the vegetative cycle definitely has an increase in yield over the same vegetative period and with a dark cycle.

If cannabis had anything that wasn't produced unless it has a dark period, auto-flower strains would be lacking if grown under 24/0 lighting. Common practice shows us that this isn't true in the slightest.

The main reason I suspect that most people agree that a dark period is healthier for plants is simple. Most growers (statistically speaking) are not that good at growing and the dark cycle is usually a relief from the stressful condition of lights on. Therefore, most plants look like they're happier after a few hours of dark.

 

[ReeferRon]

I ran both 18/6 and 24/0 in the same area with the same type bulb (CMH) for about a year each. 18/6 first and for the last year 24/0. (I use a separate flower area.)

I can report an honest 10-25% more growth and yield (Strain dependent.) from a plant that never has a dark day until its time to flower.

All of these observations were made with clones. I assume seedlings would benefit from more light as well and I just started a few packs so I guess I will find out first hand.

Some would say this isn't worth the added power consumption, wear and tear on the gear, nute use...blah blah blah. I would argue that stuff cost just a fraction of high grade marijuana.

More light more pot. My .

 

[magiccannabus]

I find vertical growth is slower, but much denser under 24/0 lighting. For most people I think that's a good thing.

 

[guidoro]

I think it depends on the light intensity.
I veg under few watts of a LED matrix and the plants are very healthy with a 24/0 cycle.
I suppose that if the light used is very intense and hot, the plant would benefit of the dark period. But in this case the problem is the excessive stress during the light period...

 

[Strainbrain]

May seem counterintuitive, but it's actually easier on a lot of electric and electronic equipment to stay on 24/0. I certainly know this from my experience using, breaking, and repairing analog synthesizers... the power-on and power-off moments are where most of the wear happens within the circuits. They rarely die after being on for 5 hours solid, rather more likely to pop when you turn them on the next time. Bulbs behave the same way, as do a lot of mechanical systems.

My only consideration on the original tpoic is that my veg box is not completely lightproof... which is only not a problem if the plants don't have a dark period. So it's 24/0 here.

Last run I vegged in the flower box, and did 18/6 after 2 weeks. I had one strain that performed much better under 18/6 and one which seems to be doing better now under 24/0.



-s

 

[bongoie]

they benifit in flower with a dark cycle , i use 24 hour with a 20w aquarium flourescent in veg / cloning it helps me regulate my tempreature

 

[crankndapot]

i think if you want faster vertical growth go with 24/0 but if u want a better root system go with 18/6. im not 100% thats right but thats my opinion. i been going with 18/6 lately just to save a little on the electric bill but id rather go 24/0

 

[Danknuggler]

they benifit in flower with a dark cycle,

Dude are you serious? They benefit in the greatest way during its flowering period to have a dark cycle as thats what makes them flower man, that quote has got to be a joke right? If so I had a great laugh if not then well read up on growing indoors more especially light scheduling for flowering marijuana. peace , nuggler

 

[IndianHay]

I think that is just too much stress for them in you ran 24/0 in veg stage. 18/6 is more normal and i will stick to that. If its some benefit its a very little one ...very

 

[Rosy Cheeks]

i think if you want faster vertical growth go with 24/0 but if u want a better root system go with 18/6. im not 100% thats right but thats my opinion.

I depends on a number of factors, but in theory you're wrong. The extra 6 hours of light per day cycle that 24/0 gives over 18/6 will result in additional vegetal mass (although the 25% increase in light does not produce 25% increase in vegetal mass IMO), yes.
But once you increase the number of dark hours, etiolation (the mechanism in which the plant 'stretches' to reach a light source, often from beneath a thick leaf canopy of competing plants) will set in and make the plant longer vertically.

You basically have the same reaction in red light vs blue light, in which the red light will make the plant grow faster but less compact, and the blue light will make the plant grow more compact, and shorter.

Provided that the light source comes from above that is.

This is one of the issues that have been discussed extensively in the forums over the last ten years, pitting emotional 24/0 veggers against 18/6 veggers. In the end, both wins. You can use both light cycles with success, so it's more about what type of plant structure you want that matters, not whether one is better than the other.

In the early days I experimented with both, and the only thing bad I have to say about 24/0 is that certain type of genetics can get stressed if vegged non-stop under strong HID lights. Although, under fluorescent lights with a high air humidity, I never had any problems.

As I said, it depends on what type of plant structure you want. Personally I veg under cold blue fluos on 18/6. The blue light used produces such compact plants that I can't even squeeze in a pinkie between the nodes. If I vegged on 24/0, the plants would be even more compact, and frankly, the motherplants would not produce good clone material, with sufficiently long stems. I have a 8 weeks minimum to veg plants between grows, that is more than enough (for me), so the extra vegetal mass 24/0 produces simply isn't necessary, only superfluous.
So, the 18/6 or the 20/4 gives the gear a few hours to cool off, and the plants to enjoy a higher air humidity. In another set-up though, 24/0 might be the way to go...

 

[hoosierdaddy]

I know there was a cat here who did an adhoc study of this last spring, and their conclusion, after weighing the final results of harvest, was that they consistently had larger harvest from the plants that had been given 20/4 light schedule.

I tend to trust a single mans study more than, 100 buffoons speculating.

 

[purpledomgoddes]

dark reactions

dark reactions

may go a little off-topic, but deals w/ dark period...

the reaction for the inc. of c02 into organic chems can occur in the dark (the 'dark reaction')+are not in strict sense part of photosynthesis. are reversal of carbohydrate catabolism... enzymes condense c02 to eventually yield glucose.

so, it would appear that c02 is used by the plants @ night (dark), if the conditions permit this. these conditions would have to be imposed by the gardener.

high vapor pressure deficit (low rh), temps (ambient+actual leaf), +availability of h20 (pressure) to roots influence stoma opening/closing.

ran cheap c02 via fermentation 24/7. 0 exhaust w/ sealed area/ac, etc. c02 constantly circulated. temps high (~78-88*f lights on, ~78-88* lights off - depending).

w/ longer days (=more energy acquired), influence (force) plant to distribute energy @ night ('dark reaction') more by raising night temps (negative diff), which increases metabolism. additionally, if there is low rh, the plant can be forced to open the stomata (usually closed/partially closed @ night, especially before dawn), to transpire in attempt to balance in/out water pressures.

once stoma are opened, they also exchange gases (i.e.g., c02). also, ppm's of nutes influence tugor pressure inside of plant, or rate/pressure @ which inorganic ions+organic molecules are pushed thru sap cell walls.

20/4 is doable+rewarding. can be enhanced more by further environmental+root h20/temp/ppm influence. higher temps (air+roots) during 4 hrs of dark, may promote greater distribution of 20 hr 'light reaction' energy.

also, since hrs of veg are in discussion, other ways of manipulating environment+plant are:

16/12, 12/16, 16/8 are other options for alternative light cycles that have been applied. diff, vpd, air/leaf/root temps all symbiotic/co-dependent though.

example: 7*24=168 total hrs per wk. in traditional 12/12, garden gets 84 hrs of dark+84 hours of light. 168/6=(6*16=96[light])+(6*12=72[dark]). this maintains the 12 hr dark period, but provides more light. then to 12/12, then to 12/16 - during final fruiting period. many options/ways to break down a 168 hr week.

plants respond more accutely to changes in environment/root zone @~ before/after dawn, when internal clock is sensitive. example: plant can be manipulated into registering warmer night than day (negative diff), if temps lowered first hrs of light. same as if human goes to sleep @ 8 every day for work in morning. if awaken @ 6am w/ cold coffee, may be in bad mood. if awakened @ 2 am, w/ cold wind blowing thru open window, will not like it period. if awakened @ 6 am w/ orange juice+smile, is generally beginning good day. living organisms are sensitive @ rest/awakeneing periods, in general.

objectively, they are only plants. do seed-run. make thousands of seeds. no loss @ all types of experimentation, both grounded in science and w/ new (your original) concepts.

hope this helps. enjoy your garden!

 

[guidoro]

Rosy Cheeks, I am very curious to see the compact structure you obtain by vegging 18/6 under blue spectrum.
Do you have any pics?

 

[greenisgold]

Rosy Cheeks, I am very curious to see the compact structure you obtain by vegging 18/6 under blue spectrum.
Do you have any pics?

I do not have pics, but I veg using a 400 watt eye blue and also have cmh bulbs and these by far create the most compact plants I have ever seen.
I was a firm believer of 18/6 for years, but now I find the best yields are found if you give your seedlings CFL light 24/0 (6000k) for around the first 2 weeks or so depending on strain. Then moving up to HIDS, dropping to 20/4 until flowering. I have tried all sorts of light times and I have found this to be the best for over all plant health and yields. I find that HIDS are just too strong for seedlings. Yes they grow great, but they seem to thrive under the mellowness of cfls for the first two weeks.