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Color Temperature vs Lumens = Confusion!

Discussion in 'Lighting' started by cRACKm0NKEY, Jun 19, 2012.

  1. 6500K For Veg & 2700K For Flowering
    How important is that? I would think that a plant vegetating on a 16,000 lumen 2000K HPS would probably grow better and faster than the same plant vegetating on a 300 lumen 6500K CFL, simply because the CFL provides so much less light (5 watt CFL vs 150 watt HPS in this extreme example). So my question is, what difference do the color temperatures actually make? I read that plants vegetating under HPS tend to grow longer branches, but what else does it do? At what point do we reach equilibrium between plant growth and lumens at particular color temperatures? For example, maybe a 6,300 lumen 6500K CFL produces similarly sized growth during vegetation as a 16,000 lumen 2000K HPS, though the CFL is both fewer lumens and watts. Any ideas? I'm vegging a single plant on a 16,000 lumen HPS right now, and wondering if I should swap it out until flowering time.

    P.S. I will eventually build a vegging box with much less ventilation, and whatever vegging light I get will go in there, so probably no MH lamps for me.
  2. If photosynthesis uses one color of light twice as much as a second color then the second color would need twice the lumens to equal the effect of the first color. This only a simple explanation, as different types of chlorophyll react to slightly different wavelengths and affecting one more than another will bring about different chemical changes inside the plant. For growing purposes, however, the specific chemistry isn't important.

    So, color temperature can be about as important as the amount of light because it affects what percentage of the light is actually used. If none of that color of light is used by the plant, then more lumens of that color won't benefit the plant in any way.

    Here's a graph of what colors of light are used in photosynthesis. It should be noted that wavelength cannot be simply converted to color temperature.

    Welcome to GC.

    Attached Files:

  3. Thanks for that explanation, and the welcoming words. Do you think I would be better off buying 80 watts of 6500K CFL lighting or just stick with my 150 watt HPS for now?
  4. depending if heats a problem. but hps is better for light penetration, so stick with that
  5. Mr. Monkey: Lighting is a very complex subject but some people try to make it a lot more complicated than I think it needs to be. First, you need to understand how they measure the light that you're using for what you want to do with your plants. I’m not an electrician and I certainly don't have all the answers but I'll try to simplify it for you.
    Wattage is the load rating of a lamp or the amount of current or electricity that the lamp draws or uses. As I recall from a Physics class I took in the mid 70's, but don't hold me to it now because I don't have the book in front of me: “Watts is amperage draw times the supplied voltage,” and it's usually read in a relatively small number. CFL’s typically draw:14, 17, 21, 29 watts. Incandescent light bulbs draw: 40, 60, 100, and MH and HPS draw: 250, 400, 600, up to a 1,000 watts. What that means is that the higher the wattage rating on the lamp the more electricity it uses and the more it costs to operate.
    That's what got us all into all those little curly-cue CFL's, (compact fluorescent lamps), and they dropped my electric bill drastically on a level pay plan to a point where I don't even get a bill from the power company for three months of the year. Before my incandescent lights were burning 60 watts each, now they’re using only 14. It makes sense.
    The really tricky part of this is that they advertise the wattage of electricity they use and the amount of light they produce and compare it to the equivalent used by an incandescent lamp putting out the same amount of light. The ones I just bought claim they only draw 14 watts but they put out the same amount of light as a sixty watts incandescent light bulb. The one I use on my clone mother draws only 29 watts but claims to put out the equivalent light of a 100 watt incandescent bulb. Now is that clear to you, or are you just as confused as the rest of us? But we're not done yet.
    Lumens is a measurement of the amount light, the intensity it projects, the brightness and that's usually measured in hundreds of lumens. I don't know where the top of the scale is but the new brighter, Ecosmart CFL lamps I just changed over to in my home advertise that they generate 850 lumens of light while consuming only 14 watts of electricity. Now you don't have to light a match to find the damned things at night when they're turned on like their earlier predecessors. My wife used to bitch that the old ones being too dim to read under but now she complains that the new ones are too bright. Go figure. Now let's consider the color of the light they're producing.
    Color, frequency or temperature of the light it produces is measured when it's run through a prism and seen in the available spectrum of colors. It’s measured in Kelvins; K's. These new lamps I bought are rated at 4,800K's, which is pretty close to the 5,000K green T-5 grow lamps I use in my tent for vegging. The lower the K's, the redder and the warmer the light. The higher the K's the cooler the light and the color goes from green to blue. Cool, green to blue light is for vegetative growth and warm red light is for flowering. Got that? If you can keep that straight think about what the sun produces during the year. In the spring and early summer the light is bright and cool, it has a higher K rating number; it's greener toward blue and our plants grow. If you have a copy of Cervantes’s “MARIJUANA HORTICULTURE THE INDOOR/OUTDOOR MEDICAL GROWER’S BIBLE,” look at page 160. Grow lamps are green to blue and that's the cool light that’s suitable for vegging. Come fall we get those beautiful warm red orange sunsets and the light is red and warm and that’s the 2,700K red light we use for flowering.
    Now let’s look at the practical side of this. I’m going to fool my plants with the right diet and lighting to go from seed sprouting to harvest in half the time they will normally need in nature. From seed sprouting through vegging I feed my babies a high N diet that’s low P and K to go along with the 5,000K grow lights and the longer lights on schedule. Right now I'm using 5,000K T-5 grow lamps for my plants to veg under. I'm told this is a moderately green light they like for growth and photosynthesis. One grower uses 6,000K's lamps and another grower uses 6,500K's. I was warned against the higher K rating by a person I trust at the hydro store. The other lamps cost a little more but my friend at the hydro store claimed he sees less light related problems with the 5,000K's so that's what I bought, and they've worked fine for me. Most people have these on for vegging anywhere from 24 to 20 to 16 hours a day. You choose.
    When my plants begin to preflower I change their diet to a lower N and higher P-K nutrient blend and the lamps in their T-5 fixture to warm red flowering lights that are rated at only 2,700K. I also drop the light interval, (the time that they're on). Some folks go directly to a 12/12 schedule but I use a progressive light schedule that starts at 20 hours of light at seed planting with 4 hours of resting darkness and I reduce the light by one hour a week. But that's another issue altogether, and I explained it here already in another post.
    After some experimentation I settled on a progression to a bottom figure of 10 hours of light and 14 hours of darkness and stayed with that until harvest. And the strains I'm growing seemed to really like it.
    So if you're asking elementary lighting questions I suggest you RTFB. Refer to the following sources: 1. Read: SeeMoreBud’s book, “MARIJUANA BUDS FOR LESS GROW 8 OZ. OF BUDS FOR LESS THAN $100.” 2. Read: Jorge Cervantes’s book, “MARIJUANA HORTICULTURE THE INDOOR/OUTDOOR MEDICAL GROWER’S BIBLE.” 3. Read: Ed Rosenthal’s, “MARIJUANA GROWER’S HANDBOOK.” 4. Read: Mc Carthy’s book, “GROWING MARIJUANA.” 5. You’ll also want to subscribe to, “HIGH TIMES,” magazine. Each issue is chocked full of useful information. .” All these resources are very well written, well illustrated and packed with information that will answer most of your questions before you know to ask them. 6. There's another excellent book I'm reading right now by Greg Green called, “THE CANNABIS GROW BIBLE-SECOND EDITION,” it’s every bit as good as the ones I mentioned above but a lot more technical. All of these resources are available at major book stores and at most growing forums. They will save you and your plants a lot of stress. The only problem with these forums is that if you get in a jam and need help right away it may be a while before we can get back to you. I sincerely hope this helps. Hank

  6. What size is your growing area?
  7. Mr. Monkey: Listen to Jellyman, he has a good point. Your lighting has to fit the size of your grow space and that comes under planning which is well covered in a number of good resources. I wish there was an easier way, but from what you ask, I think you might be new to this so I’d suggest you RTFB and refer to the following:
    1. Read: SeeMoreBud’s book, “MARIJUANA BUDS FOR LESS- GROW 8 OZ. OF BUDS FOR LESS THAN $100.”
    3. Read: Ed Rosenthal’s, “MARIJUANA GROWER’S HANDBOOK.”
    4. You’ll also want to read: Mc Carthy’s book, “GROWING MARIJUANA.”
    5. You should also subscribe to, “HIGH TIMES,” magazine. Each issue is chocked full of useful information. .” All these resources are very well written, well illustrated and packed with information that will answer most of your questions before you know to ask them. And I want to add a new book to the list, a 6th one: “THE CANNABIS GROW BIBLE- SECOND EDITION,” written by Greg Green. It’s a match to, if not better than, the ones listed above. Doing your homework and consulting these resources will save you and your plants a lot of anxiety before you plant. These forums are great but often they can’t get the information you need to you in a timely fashion. I hope this helps. Hank

  8. Thanks! Straight to the point.

    2x2 feet and 4 feet tall. Just one lonely plant.

    Complicated post aimed at uncomplicating things? You even pasted in a page number ;)

    I've read a lot on the subject. Pretty sure I even read that paste job you just did in other peoples' posts too. This is my second grow, but my first was several years ago. I didn't see anywhere that speaks of specifics of growth size when the most ideal solution is not used. Most literature, much like what you pasted/posted, just tells you what is ideal. My specific question is, would 80 watts of CFL cool color temperature lighting be better for vegging than 150 watts of warm HPS light (assuming the usual lumen count for those types of lights)? For my single plant grow space (2x2), the books say 1600 lumens of cool light, which is not an option. Find me a book with a chart or something that can answer my specific question above, and I'll send you a cookie.
  9. If you want to upgrade your light, you should replace the 150w rather than adding smaller bulbs to it. You can use up to a 400w for maximum potency & yield in that size area. I typically use a 400w for a similar floor space with four 5gal buckets.

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