lighting 24 Hour Lighting?

The_NorthEast_ChileMan said:
 
As you experience, our northern location and because nights are light from the end of May to the beginning of August there is daylight in summertime around the clock across the whole of Finland. Lapland, north of the Arctic Circle, has “nightless nights” in the middle of the summer, when the sun does not sink beneath the horizon at all., how do your plants do outside? Do you try to shade them? Do you think they'd do better with rest?
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I dont need to do anything special for my plants, just place them inside the greenhouse and pray for a good summer. :rofl:
 
hardcore said:
the pepper plants will fruit  under 24 hrs lighting?
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No, never tried that.
My answer was to AJ's question ," Any detrimental effect on 24 hour lights?"
 
My 24/7 lights and sunshine and lights take my plants from germination to 3 months , when the first flowers appear .
 
After that it stays outside.
 
Wow, reading the different approaches for different climates is great.  Here, I can't start outdoors at all.  Just not enough time.  Even with a high tunnel or greenhouse, unless they are heated it wont work.  Then there is summer.  Just put a plant into a high tunnel or greenhouse and expect it to perform isnt too wise because of the heat.  I have to have the plastic off by July or flowers drop everywhere.
 
In general, I plant indoor December / January (some later) and they can go into the high tunnel in May, but only because I put portable heaters in there when I am worried.  It is a gamble every year because it is not until Jue that you can be absolutely sure they will be OK.  Still, I plant earlier hoping for the best and keeping some for reserve.  Basically, I never plant all of a thing till I know we wont have any more cold weather.  Things here are so weird now a days.  A couple years ago, we still had peppers in the high tunnel till almost Christmas.  Last year, Frost took everything just after Halloween.

So I never count on anything from the business after Halloween now.  Anything after that is more of a better Christmas for the kids.
 
Published this not too long ago if it helps
 
 
Most works on artificial lighting of winter greenhouse vegetable crops studied the effects of photosynthetic photon flux but rarely photoperiod.
 
Over the last three years, we conducted experiments to find out the best photoperiods for production of greenhouse tomato and pepper.
 
We found that extending photoperiod up to 20 hrs increased productivity of pepper plants while continuous light (24 hrs) decreased yields. For tomato plants, productivity reached a maximum under a 14-hr photoperiod while longer photoperiods (16 to 24 hrs) did not increase yields.
 
For both pepper and tomato plants, optimal growth (shoot fresh and dry weights) was obtained under the same photoperiods that gave the best productivities.
 
 
 
We also observed leaf chloroses on tomato plants after 6 weeks under photoperiods of 20 and 24 hrs and leaf deformations (wrinkles) on pepper plants exposed to continuous lighting.
 
We also observed that plants under continuous light grew better and flowered earlier during the first 5 to 7 weeks of treatments.
 
So, tomato and pepper plants can use advantageously continuous supplemental lighting for a short period of time but are negatively affected on a long term basis. Future works should look at varying photoperiods to optimize yields.
 
 
 
 
 
Source: Dominique-André Demers, Martine Dorais, Serge Yelle and André Gosselin from the Centre de recherche en horticulture, Département de phytologie, Université Laval.
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If you like reading academic papers here another interesting one regarding photoperiods. ---->>> http://www.nrcresearchpress.com/doi/pdf/10.4141/cjps89-159
 
ELCouz said:
Published this not too long ago if it helps
 
 
 
If you like reading academic papers here another interesting one regarding photoperiods. ---->>> http://www.nrcresearchpress.com/doi/pdf/10.4141/cjps89-159
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I agree , but that is focussed on production and adult plants.
Back to AJ question, Is it detrimental to his young plants before he puts them outside in his tunnels for their adult growth and production.?

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I grew under 24/7 lights in 2015 when my cheap timers bit the dust, and had a ton of healthy plants on my hands.  They were on for 3 months straight...  from first seedlings sprouting to the time I started hardening them off. 
 
This year with the high output T5's I'm limiting their light to 16/8 - the light is so intense that the plants show sunburn even on that schedule.
 
Plus they're growing so damn fast I might run myself out of room by the time I plant out in May. :)
 
I have 1" long true leaves already on plants which were seeded 16 days ago...
 
 
TrentL said:
Plus they're growing so damn fast I might run myself out of room by the time I plant out in May. :)
 
I have 1" long true leaves already on plants which were seeded 16 days ago...
 
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Ye, I hate to say it but I still have things to plant and this is completely intentional due to the running out of room issue.  I am fairly sure by starting later than last year I can actually grow more.  Either way, I really need more room.  Am thinking about one of those south facing green houses where the North side is completely insulated and the south side is at a very steep angle to meet winter sun and bounce some of the summer sun.  Who knows, maybe heating one would be offset by some of the sunlight that I dont have to reproduce with lights.

Its kind of funny to note I thought I had a good frame of reference on growing peppers from more traditional crops.  Tobacco, soy, and corn are very big here.  But most of the peppers we grow are so very long season that I am kind of figuring out the business end as I go.  How early to start, how much does electricity cost, how much to heat a green house, its all fairly new so I have very few people to ask.  Lots of information on how to grow, but how to grow AND profit enough to accomplish X, Y, and Z is kind of new territory.  Not a lot of folk doing it.

Best Example: Wanted to go LED to replace some ballasts.  Great idea for growing cannabis indoors.  But finding lots of nurseries sticking with metal halide because they benefit from the extra heat in a green house. Now I know it is not a very energy efficient way of producing heat, but heat concerns are one less reason to use LEDS when you are doing it in a green house.  In a home, you gotta worry about too much heat.  In a green house in winter or spring, just the opposite.
 
Yeah I kind of jumped in with both feet this year myself. Bought a farm in December and decided to carve out some of the field for a pepper / tomato crop.. 
 
Deep winter greenhouses are on the list to build this year, as well as more traditional ones. I have a design I made on paper two years ago for a deep winter greenhouse that I've been sitting on, going to give it a run this year.  Should double as a good drying house in the late summer / fall too, for dehydrating strung peppers.
 
Starting plants indoors and going through the hardening off process is a major PITA and isn't going to be viable when I scale up further. I'm pushing the limits of what I can do indoors this year, big time.
 
 
 
We have one high tunnel.  For hardening off, I have started putting black plastic over it and then gradually pulling it off on one side.  I also use heaters and gradually decrease the heat.  It is the best thing I have come up with so far.  The whole moving them outside and inside thing just wont work.  I suspect that if we start in a heated green house, that even if we are using artificial lighting there is enough sunlight to decrease the need to harden off for light.
 
I hesitate to offer much advice or make too many conclusions from multiple data sets without controls, but for what it's worth, 36-40 hours on and 12-8 hours off didn't seem to harm anything (small plants from ~ 2 sets of true leaves until forking) in my hands. This was under LEDs (viparspectra 450w).
 
That would seem to at least match the one scientific paper mentioned by ELCouz.
 
If you're looking to get an answer for high investment/profit ratios, it's a very difficult question (as you've specifically mentioned AJ) because maybe you don't want plants growing as fast as possible indoors. Is the extra head start and larger plant mass going to offset the extra space/electricity cost? Will those larger plants produce enough fruit to make it worth it? I don't have any solid evidence for this statement, but I doubt the investment to make the jump from 12/12 to 16/8 (or more) will pay for itself very quickly - and maybe it never will.
 
It's obviously difficult for hobby growers (or small commercial) like us to dedicate the resources for proper experiments.
It means multiple sets of lights, lots of space, essentially guaranteeing either plant death or extremely stunted growth, and time dedicated for quantitative measurements.
 
There's a lot of experiments I would like to try myself, but currently I've settled into more of nutrient based mini-experiment.
 
I run 24/7 and my peppers are fruiting. I've read many different articles and decided to try it on my own.

Works well.

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On fruiting under lights.  Over the years, have noticed the strangest thing.  They fruit under lights, go outside and stop.  My first thought is the change in light cycle, but they are reportedly light neutral when it comes to fruiting.
 
AJ Drew said:
On fruiting under lights.  Over the years, have noticed the strangest thing.  They fruit under lights, go outside and stop.  My first thought is the change in light cycle, but they are reportedly light neutral when it comes to fruiting.
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They go in a state of shock when you change the growing place and may need many weeks of recovery from that to start fruiting again.
 
I ran my jalapeño and poblabos under 24hrs LED last yr from when they germinated until I started hardening, and the plants were dark green and robust, and produced truckloads of fruit.

The rest thing, at least for those varieties, is BS.
 
That article breaks down the lighting conundrum into intensity, and photoperiod.  The way I read it, there is a relationship between light intensity at given intervals, and overall plant development.  The intensity at given times, and up to a certain level, are more beneficial than just pure exposure, at any level.
 
I can tell you that we have the highest UV index in the country right here, and my plants don't look better than those grown elsewhere.  Of course, there are other environmental conditions must be considered.  But all in all, this article suggests that running 24/7 is a waste of electricity.
 
I'd be shocked if anyone could prove that you can get (statistically significant) higher yields at 18-24 hours of lighting, than 6-8 hours of proper spectrum lighting.  In fact, that's a challenge, to anyone with the resources to conduct such an experiment.
 
Those expiriments exist online, and the results were undeniable. Thicker stems, larger plants, earlier fruit, and for some plants early enough an entire second set of fruit was obtained. check out garden Web.

I'm not in this to shave pennies on electricity. Gardening at this scale is break even at best when you account for all the variables. I'm doing it for quality, and a hobby.

But if this is your primary source of sustenance, and you're trying to do it to save money, by all means, throttle your electicity bill. You'll be fine.

I'm just saying there's not only no detriment to running 24hr light on your seedlings, the only decent online expiriments on the matter prove out my experience. When I hardened off, I had more robust plants, and a better crop.

That plants need rest, at least for that stage, is nonsense.
 
The point that I was trying to make, is that the article refers to "supplemental" lighting.  The research was done in Canada, where the incidence angle of the sun is much shallower than places near the equator.  During certain hours of the day, additional lighting was applied, to mimic higher intensity light. (to mimic something closer to say, that of the equator, where incidence angle is steepest, and therefore, provides most intense light)
 
The article did go on to correlate lesser yields with 24 hour lighting. 
 
I don't disagree that you will not *harm* plants by running lights 24/7.  But I think that what I got out of the reading, more than anything, was that you don't need persistent lighting - just the CORRECT lighting.  You can run a more intense light on an interval, get the same result, and spend less money doing it.
 
Anyone growing above the tropic of Cancer, or below the tropic of Capricorn, receives much less intensity from the sun, than those of us within the same bounds.  So while it may be longer lighting period, it's not the same quality of light.  So this study was well worthwhile, in that context.  But again, I reiterate...  Environmental factors play a huge role, also. (not to ignore the fact that the article related higher growth rates with CO2 supplementation and high PAR) Change any one factor in a different location, and you may get hugely different results.  A base comparison of lighting isn't sufficient.  Do the same test in different areas.  See what you get.
 
I agree that there's lots of tests on photoperiod.  From research, and personal experience - in this case, for peppers - my verdict is still that proper lighting, with a proper time interval, and optimal environmental conditions, produces the best end product.  This is a well supported hypothesis...
 
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