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Do plants need any darkness?

Paul44

Paul44

Should I give established (over 2 feet tall) plants any darkness or can they handle 24 hours a day of light? I think that a while ago I have seen a topic on this but I cant seem to find it again.
 
Any answer appreciated,
 
Paul.
 
Brain Strain Pepper Head said:
I have left mine on 24/7 under a 1000 watt HID for months and when I was in Alaska they got light 24 hours during summer so my answer is no but of course you will have the Nay Sayers
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Dang, what was the energy bill for that HID?
 
I had 3 lights all 1000 watts on 24/7 and it raised my bill under $100.But since this is my only hobby and don't drink or smoke its worth it. Now I have 3 lights on 16/8 and it runs about $100 more with fans and a heat station. But since it's really my only expense I can afford $25 a week...
 
I think its good for plants to have alternating periods of light and dark.. They have circadian rhythms just like we do...
 
And i've read that the dark hours is a time of vigorous growth for the plant. While light is hitting it, it is busy undergoing photosynthesis and a lot of the sugars made get stored. Once it gets dark and photosynthesis stops those stored sugars being to be used to build up new cells..
 
Of course the amount of time varies between plants. I've heard a lot of people on here say 16 hours of light for peppers..
 
But it sure ain't gonna kill it.
 
Proud Marine Dad said:
Will a pepper plant flower if given 24/7 light?
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That's a really good question also. I am interested in the flowering implications also.
 
Thanks for any assistance,
 
Paul.
 
Photo inhibition is a process when a plant is overloaded on light, and because it can't absorb anything more until the leaves "cool down" it will get a sunburn. With peppers though, this takes a LOT of light over a lot of time, and if it's dim enough then it shouldn't be much of an issue.
 
I am not an expert and still experimenting but I have given my plants non stop light on a few occasions and by the third day they really appreciate 6 hours of darkness. After that 6 hours of darkness they explode with new growth. I have settled on 16 hours of light a day.
 
I don't think it will hurt anything to keep lights on like that for a while, but I tend to look at what happens without human intervention for a clue. It seems to me that all living things need periods of rest. Some need more, some need less. The real question is what happens over time - just like you or I can go a night without sleeping, give it several nights and we finally zonk. But then, we are of a higher order than plants. Could be, though, that extended periods without darkness would adversely impact production - if not for one season, possibly over the life of the plant, which might be reduced in such circumstances. But that's an untested hypotheses on my part. Also, as noted by PJ, and as witnessed by many of us here, plants can make huge growth spurts overnight, and this seems to be dependent upon that period of darkness. It would be interesting to start two of the same kinds at the same time, and subject one to 24/7 light but keep normal light/dark patterns going for the other, and see what happens over an extended period of time, such as 5+ years.
 
For those with a desire to read technical papers have a look at "Plants Under Continuous Light: A Review". I had previously read articles on light times and tomatoes and chili plants in the past. From what I could recall chili plants had really benefitted from continuous light for the first 5-7 weeks, but after that the photoperiod had to be reduced otherwise leaf chlorosis had occurred.

After briefly skimming the article in the link below, the effects of light time for better or worse really depends on the plant. It would appear that a LOT of research has been devoted in an attempt to answer this question over the last 91 years.

http://www.globalsciencebooks.info/JournalsSup/images/Sample/PS_4(1)5-17o.pdf

Neil
 
This question has been asked before...although peppers are not photo-sensitive when it comes to blooming and fruiting, the real question is how much do they need? Anything beyond that is wasted $$$ on your energy bill. I did a time lapse video of how my plants reacted during the light and dark cycles a couple years ago...
 
You can see in the video that toward the end of the light cycle the plants start to droop very quickly and then bounce back once the lights go off.
That first link may not work for everyone do to copyright stuff because I put it to music...if that's the case here is some raw footage.
After this video I have never run my lights past 14 hours on 10 off and have not noticed any drop in growth rate. Hope this helps answer your question.
 
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