Yea quite a bit of work for a popsicle 
Yup Fremont Iām off of 580.
Okay. I have a question similar to this, but not exactly the same. I have a naturally lighted 4 season greenhouse and I am keen to NOT use supplemental lighting or blackout cloth. I want to vegetatively grow my plants into the winter and then allow them to flower naturally in the spring when the day length is appropriate. As I understand it, I can delay flowering by interrupting the dark period with supplemental light. Is this possible and if so, what is the minimum light period needed? And what is the minimum PAR needed. Thank you for your help.
Cannabisā ancestry is well accepted to be near the Hindu Kush of northern Pakistan and Afghanistan, and ruderalis is considered the closest to the archetype ancestor of all cannabis. Its territory stretches from the Hindu Kush of northern Pakistan and Afghanistan, stretching through northern China and Russia near Siberia.
Regular photo period strains of cannabis do not naturally flower in the spring. Cannabis naturally flowers when the days get shorter, to survive the winter, the seeds have a better chance at surviving the winter than the plants will.
Even equatorial sativa strains predominantly flower in the fall/winter, although near the equator you might be able to get two harvests annually. Typically any photo period strain of cannabis needs about at least 12 solid hours of darkness or more to induce flowering.
You can indeed delay flowering by interrupting the dark period with supplemental light.
~MacG
Great! As an retired horticulturist, I am well versed in photoperiod and flowering triggers. I have, with other species, forced flowering in similar circumstances, however, I have yet to find information on the length of time and PAR required to delay flowering with my new plant partnersā¦ So an hour with lights on? A 100 W incandescent bulb good enough? Thanks again!
I wouldnāt use a typical or traditional incandescent light, not enough blue light to keep a plant healthy.
For flowering you want about ideally 50 watts per square foot with horticultural HID lights for indoor growing. You can probably get away with a little less than 50% for veg. So about 25 watts per square foot would probably be plenty, for veg.
For fluorescent lights, especially CFLs and T5s, and even more so for these lights when specifically designed for plants, 40-45 watts per square foot is enough for flowering. Keep in mind, part of the reason you can get away with less watts is because you can bring fluorescent lights closer, as they donāt create as much heat at the bulb as HID lights do, and so the lumens are more intense due to proximity and the inverse square law of radiation, not because they create as many lumens/PAR per watt at the bulb. A note to keep in mind especially about āhousehold CFLsā, is we are talking actual watts, not equivalent watts.
With good quality LEDs made for plants you can get as low as 30-35 watts and still be efficient and effective for flowering. But that is because you can turn nearly 100% of the watts into only PAR. White light is roughly made up of equal parts red, green and blue light. In simple terms plants only need the blue and red light and so you can effectively save up to a third of your electrical watts by not wasting it on green light. LEDs generally are not as hot as HIDs either, and some of the increase in efficiency could also again be due to proximity and the inverse square law that describes the diminishing intensity of radiation over distance.
I havenāt put the work in to translate the numbers into PAR yet, nor found a similar list in PAR yet, but here is a list of needed lumens:
Seedlings and clones require about 400-1000 lumens per square foot.
Vegetative growth requires about a minimum of 2,000 to 3,000 lumens per square foot.
Flowering requires about 5,000 to 10,000 lumens per square foot, ideally, and can take possibly much more.
10,000 lumens is supposed to be about the average power of the sun at sea level on a clear day at high noon. 8,000 ā 12,000 lumens is supposed to be about the average power of the full sun without any overcast or no clouds, depending on altitude and potentially other factors. In the high altitudes of the Himalayas and Hindu Kush mountains (the ancestral home of cannabis), this means probably leaning towards the higher numbers on a clear summer day as there is less atmosphere to filter out some of those lumens.
Itās not ideal, but you can make do with 2,000 lumens for an entire grow if necessary.
High pressure sodium (HPS) is heavy on the red side of the spectrum but has enough blue to keep your plant healthy through all phases of growth.
Metal Halide (MH) can be better tuned to a closer spectrum matching natural sunlight but is not as efficient in the conversion of watts to PAR as HPS, so you get more bang for your electrical watt with HPS. LEDS are among the most efficient as they can deliver specifically PAR only, and no other parts of the electricity is wasted on non PAR parts of the electromagnetic spectrum.
Most commonly found in MH and fluorescent lights youāll see a color rating based on the āKelivinā color scale, the higher the number the more ācoldā or blue/violet the light looks and in general the more of this side of the electrical magnetic spectra is represented, the smaller the number the more āwarmā or orange/red the light looks and in general more of this side of the electrical magnetic spectra is represented.
5500K to 6000K is the color of sunlight at high noon and is generally considered pure white or true white. 5000K to 6500K is the color of sunlight with various other conditions, including just before sunset and still bright(5000K) and overcast and kind of bright(6500K). Yes, the more exact color might change depending on altitude, possibly latitude as well as season, as this will change the amount of atmosphere the sun goes through and more atmosphere may further yellow or redden the hue of the sunlight, not unlike the way sunsets are more orange or red than the way the sun looks most pure white at high noon(5800K) when it is passing through the least amount of atmosphere.
Here is a break down of the electrical magnetic spectra near the photosynthetically active radiation, or PAR, range:
720 - 1000 nm There is little absorption by chlorophyll here. Flowering and germination is influenced. At the high end of the band is infrared, which is heat.
610 - 720 nm This is the red band. Large amount of absorption by chlorophyll occurs, and most significant influence on photosynthesis. (promotes flowering and budding)
520 - 610 nm This range includes the green, yellow, and orange bands and has less absorption by pigments.
400 - 520 nm This range includes violet, blue, and green bands. Peak absorption by chlorophyll occurs, and a strong influence on photosynthesis. (promotes vegetative growth)
380 - 400 nm Start of visible light spectrum. Process of chlorophyll absorption begins. UV protected plastics ideally block out any light below this range.
315 - 380 nm Range of UVA ultraviolet light which is neither harmful nor beneficial to cannabis plant growth. Although some studies do seem to indicate this band might stimulate resin production, as THC does seem to have UV blocking properties, and these frequencies may be able to stimulate the plant to create these UV protecting resins without actually having toxic or negative effects on the plantās biological function.
280 - 315 nm Includes harmful UVB ultraviolet light which causes cannabis plants colors to fade.
200 - 280 nm UVC ultraviolet range which is extremely harmful to cannabis plants because it is highly toxic.
And above these wave lengths dwell the very long radio/TV waves (even microwaves), and below it resides the ultra short X-rays and gamma rays.
It is a lot of info, but I think I got you covered in most ways I could think of pertaining to your questions.
~MacG
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Wow! Thanks, you have an impressive amount of knowledge, but Iāve got plenty of natural light to grow. I live in the high desert, very similar to Afghanistan and Pakistan. I have more than 325 days of clear skies and quality sunlight. As I do not want to invest in lighting, I was hoping to discern if someone had documented the minimum PAR and the lenght of time needed to prevent or delay flower initiation. If you donāt know fine, I really am thankful for you taking the time to reply. Iāll just work empirically. BTDT. Again, wow! I really appreciate your consciencious and time consuming effort. I only wish I could do the same for youā¦ Thanks!
I believe about 14 hours of light is about the minimum to guarantee continued vegetative growth without flowering for almost all strains of cannabis, auto-flowers excluded. The minimum degree of intensity Iām not entirely sure of, Iād imagine it might be near that 2000 lumens minimum for a healthy adult plantās vegetative growth.
@latewood has a ton of greenhouse experience and can maybe give you more specific info or recommendations, I tagged him in this sentence, so heāll get a notice and can comment when he next has a chance.
But Iād imagine a few 25-45 watt common household 5000k-6500k CFLs placed near and around the plants, turned on in the āgas lantern routineā would probably work fine for your purposes.
Do a general search for it on google or other search engine if you are not already familiar with the term.
Just keep in mind, light stress has been known to contribute to hermaphrodites in some strains and light schedules outside of nature might not be the best to avoid this type stress. We normally recommend consistent reliable light schedules without interrupting the dark cycle for best results with strains susceptible or known for hermaphrodites.
~MacG
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14 hours of light is teetering on the edge. After enough time; I believe plant will flower. Reading that you want to veg for 3-5 months whatever your winter is; Is going to be a chore. I would make sure to have 15-16 hours light minimum.
.
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I know itās not all in the same thread, so it is a bit confusingā¦
But he actually is finished, and you can see the finishing up and manicured buds on the plants in the green house, if you can see it. I know your eyes are not the best my friend.
~MacG
Didnāt mean to confuse anyone my apologies have a nice rest of your evening.
It is a beautiful picture! Nothing to apologize for.
~MacG
Hell; I want to live there!
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Awesome view, and that sunset, but then you got thoughs buds peeking through the Windows
Great job brother
Will
Awesome picture lolš
I just started my grow and all excited I went out and bought those 120w Philips agro plant lights 
all to hear how useless the incandescent light bulbs are 
but with the agro lights they are supposed to have a coat of something filtering out āyellowā colors in light wouldnāt that also remove the green and make these lights useful? And can I put like a piece of glass in between the lights and my plants to get the lights closer and reduce heat? @garrigan62 @MacGyverStoner @latewood
As far as im concerned the glass wonāt keep down your heat as for the yellow and green im going to let MacG take that one. He has far more knowledge than I on that oneā¦sorry. but heāll help you. And im looking forward to more picās of your greenhoue grow the other oneās were breathtaking.
Will
Will
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I would make sure to monitor the top of the plants for scorching. Maker sure to keep 1 dedicated fan blowing between the glass and the top of the plant canopy
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I switched to cfl btw. Those bulbs were way too hot for not enough light