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Offlineicanfeeltherain
Newb Mycologist
Male


Registered: 10/26/08
Posts: 53
Last seen: 6 years, 4 months
Color Temperature of lighting
    #394026 - 04/01/10 08:02 PM (6 years, 7 months ago)

What is the best K value to shoot for at each stage of development?  I assume go from low to high moving from veg to flower?  Could putting seedlings under 3500K "white day light" cfls and then moving to veg under a 2300K MH result in any stress or poor result?  Four 26w CFL (equal to 100w incandescent)  looks good for a couple square feet right??

Thanks!


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"We are here to awaken from the illusion of our separateness" - Thich Nhat Hanh

"Yes, Cuban B."


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OfflineUnion420
Horticulturist

Registered: 03/04/10
Posts: 94
Loc: New World
Last seen: 6 years, 7 months
Re: Color Temperature of lighting [Re: icanfeeltherain]
    #395495 - 04/03/10 10:22 PM (6 years, 7 months ago)

You want around 6500 for veg more blue light, it cuts down on stretching and makes more veg growth along with helping to encourage females when growing from seed. 3 and 2700 are better suited for flowering.


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Offlinesnufkin
Male
Registered: 10/14/08
Posts: 99
Last seen: 5 years, 7 months
Re: Color Temperature of lighting [Re: icanfeeltherain]
    #395680 - 04/04/10 09:28 AM (6 years, 7 months ago)

In my experience the 2700K are useful throughout the whole process, but you want to supplant it with 6500K "daylight" to prevent excessive stretching. This is most important in the vegetative stage, but there is not harm in keeping them around for the flowering stage.

Cannabis makes good use of this spectrum. Around 3000-5000K has a lot of its light in the green portion of the spectrum. The plant has no use for green light.


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OfflineUnion420
Horticulturist

Registered: 03/04/10
Posts: 94
Loc: New World
Last seen: 6 years, 7 months
Re: Color Temperature of lighting [Re: snufkin]
    #397303 - 04/06/10 11:13 PM (6 years, 7 months ago)

The problem with more red in the spectrum prior to pre sex is it encourages males, where blue does the opposite so your chances of getting more females are higher using more blue, Ive done tests to back this up and plan on doing a grow log in the near future to express this and make my findings aware to the community as there is very little info on this at this point although its very usefull and most important is it works. Ive never went back and never will now.


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Everything is fictional, I dont even exist.


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OfflineDieselB
High Watt Closet
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Registered: 02/10/10
Posts: 1,156
Last seen: 1 year, 8 months
Re: Color Temperature of lighting [Re: Union420]
    #397381 - 04/07/10 01:04 AM (6 years, 7 months ago)

You're probably not gonna find a metal halide in anything near 2300k, when you are ready to make the switch to HID you don't have to worry too much about color temp.. So long as you are using decent "grow" bulbs the spectrum will be what you need (MH=Veg/HPS=Flower).

Or, as stated above, you do have the option of using the HPS throughout the whole grow, quite a few people do this with good results.. I personally feel that it's much more productive to use the MH for veg. Usually the bigger/heartier you get them during veg, the higher the yield.


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If you ain't smokin' dro, you're smokin' reggie. :shrug:


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OfflineUnion420
Horticulturist

Registered: 03/04/10
Posts: 94
Loc: New World
Last seen: 6 years, 7 months
Re: Color Temperature of lighting [Re: Union420]
    #397732 - 04/07/10 04:47 PM (6 years, 7 months ago)

I dont even use MH, I use 100w CFL floods made by lights of america. Its not the twisty bulbs that say 100w but are actually only 20 or whatever (they vary) I think thats a big misunderstanding for people when they get into CFL's they see 100 or 200 or whatever really big on the package but in reality the light is only good for about a quarter or eight of that as they advertise as equivalent to 100 or whatever it may be, and the word equivalent gets misunderstood.

Depending on the size of the grow, (for instance I use 4) using these particular CFL's can be impractical in say a warehouse or large setup but for a 4 by 4 veg room or even 10 by 10 they are great. The most important time to use them is when growing from seed, which dosent require large area or light. Once sex is determined the MH can take over or you can continue to use these obviously depending on the situation. What I usto do is germ 10 to 50 seeds at a time under 4 of these then when sex was shown Id move in the MH and let that take care of veg, cloning ect. I have no use for the MH now since I only veg a week or two and only have 1 to 5 active mothers at a time so the need for extra light is not there.

The reason I dont use MH untill after sex is shown is the high levels of UV which can contribute to stress in turn encouraging males, once sex is shown this is no longer a issue. The spectrum in MH is great for veg tho.


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OfflineDieselB
High Watt Closet
Male

Registered: 02/10/10
Posts: 1,156
Last seen: 1 year, 8 months
Re: Color Temperature of lighting [Re: Union420]
    #397743 - 04/07/10 05:01 PM (6 years, 7 months ago)

I really don't think the MH contributes to males, especially not because of the uv.. If that were true there would be alot more than 50% chance of males outdoors. My current grow, out of twenty bagseed plants, I have about 15 females, and they are growing under a 600w metal halide.


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If you ain't smokin' dro, you're smokin' reggie. :shrug:


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InvisibleDoPeYsMuRf

Registered: 08/14/09
Posts: 645
Re: Color Temperature of lighting [Re: icanfeeltherain]
    #397795 - 04/07/10 06:38 PM (6 years, 7 months ago)

I've been doing alot of research on light and how it effects plant growth and there's literally thousands of articles on the subject.

I'll try to relay some stuff based on what is already being discussed in the thread.

I'll also try to give credit to specific citations throughout my thread.

I have found no studies that indicate red light has any effect on sex ratio. UV does in fact effect plant growth to some degree.

In particular UV-B causes seedlings to grow slower and have narrower leaves. But studies show that UV-B also decreases the chance of insect infestation by up to 50%!

Red spectrum triggers hormones in the plant which stimulate flowering and budding.

I just read a study describing how when plants are planted in rows, the closer they are together, causes far red light to reflect more causing greater internode distance and less branching.

Blue spectrum promotes branching and causes closer internode spacing. Also blue light regulates the opening response of stomata.

That's why its important to use a blend of blue and red light for flowering.

Another study I just read used a 4/1 ratio of red and blue light and they discovered an increase in dry matter.

I think the reasoning behind this was something to do with since blue light is primarily used in nitrogen fixation it allowed more CO2 via transpiration. I can't remember exactly and cannot find the study either.

Contrary to popular belief "green light has been shown to act as a signal in regulating specific facets of plant physiology, inhibiting seedling mass, plant cell culture growth, and light-induced gravitropic root elongation" (Klein, 1992)

I really want to keep going but this got boring really fast. Therefor I will end here.


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OfflineDieselB
High Watt Closet
Male

Registered: 02/10/10
Posts: 1,156
Last seen: 1 year, 8 months
Re: Color Temperature of lighting [Re: DoPeYsMuRf]
    #397799 - 04/07/10 06:44 PM (6 years, 7 months ago)

Good stuff, Dopey, thats pretty much in line with my theory. The insect part is particularly interesting. Maybe you could post some links for us nerds who like to read through the "boring" stuff.


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If you ain't smokin' dro, you're smokin' reggie. :shrug:


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InvisibleDoPeYsMuRf

Registered: 08/14/09
Posts: 645
Re: Color Temperature of lighting [Re: DieselB]
    #397800 - 04/07/10 06:46 PM (6 years, 7 months ago)



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