Kandy: 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 the vocabulary of 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 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 current/amperage draw times the supplied voltage,” and it's usually read in fluorescent lighting 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 1,000 watts. What that means is: the higher the wattage rating of the lamp the more electricity it uses and the more it costs to operate per hour. I think that’s the important thing to know about wattage.
That's what got us all to convert to those little curly-cue CFL's, (compact fluorescent lamps), and they dropped my electric bill drastically on a level pay plan to the 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 compared 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, lumens, 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 brightness of a 100 watt incandescent bulb. Now is that clear to you? Or are you just as confused as everyone else? But we're not done yet.
Lumens are a measurement of the amount light, the intensity/brightness a lamp projects and it’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 for what we want our plants to do.
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 my 5,000K green/blue 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 would 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 time period the lights are on. 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 I know uses 6,000K's lamps and another 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 they're on). Some folks go directly to a 12/12 schedule but I use a progressive light schedule. Mine start under 5,000K lamps for 20 hours of light at seed planting with 4 hours of resting darkness. I reduce the light by one hour a week. They start preflowering at about 14 hours of light and 10 hours of darkness and I change the lamps to red 2,700K’s and their diet to a lower N and higher P and K for flowering. But the progressive light schedule was a brain fart of one of my teachers and that's another issue altogether. I’ve already explained it here 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. Read Greg Green’s, “THE CANNABIS GROW BIBLE-SECOND EDITION,” it’s every bit as good as the ones I mentioned above but, like Rosenthal’s, it’s a lot more technical.6. You’ll want to subscribe to, “HIGH TIMES,” magazine. Each issue is 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. 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