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Thread: How many lumens for my grow area?

  1. #1
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    Question How many lumens for my grow area?

    how many lumens of 6500k cfl lights do you need for one plant with a height space of 5 ft high?

  2. #2
    420 Member ilikebike's Avatar
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    Re: how many lumens for my grow area?

    not sure on the lumens but if you got (8) 25w CFLS that thing would grow nice and fast. Then just switch the bulbs to 2700k CFL's and your stylin

  3. #3
    420 Member Fuzzy Duck's Avatar
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    Re: how many lumens for my grow area?

    Not that plants have human eye balls to see lumens...

    Lumens per square foot:

    Minimum amount of lighting needed is around 2000 lumens per square foot.
    Mid range is around 5000 lumens per square foot.
    Optimal is 7000-7500, or higher, lumens per square foot.

    Watts per square foot (wattage per sq ft WILL vary by light source):

    Minimum wattage per sq ft.: 30w
    Mid Range wattage per sq ft.: 50w
    Optimal Range wattage per sq ft.: 50-80w

    To most accurately ascertain the proper amount of lighting needed for your space, there are several things that you have to know. At this point, a couple of definitions are in order.

    Lumens - one lumen is equal to the amount of light emitted by one candle that falls on one square foot of surface one foot away.
    Watts – A measure of the amount of electricity flowing through a wire. Watt hours measure the amount of watts used in one hour. A kilowatt/hour (KWH) is 1000 watt/hours.
    Light Spectrum – In simplest terms – Blue (425nm – 460nm, think a 6500k CFL or MH) & Red (630 – 660nm 2700k CFL or HPS). Blue wavelengths are associated with vegetative growth, and reds with rooting & blooming.

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    What to do with it all
    To determine how many lumens per square foot you have:

    Find out the square footage of your space.
    Width x Depth = Square feet. Divide the lumens available by your square footage.
    This will give you lumens per square foot.

    Example: Say your space is 3 feet deep by 4 feet wide, 12 square feet. The total lumens available from your light(s) is 45000 lumens. 45000/12 = 3750 lumens per square foot.

    What if you want to determine how much light you need in watts?
    The general rule of thumb for providing light for an area is a minimum of 30 watts per square foot. 50+ watts per square foot is optimal. You can determine the proper lighting for your area by using this formula:

    50 watts (or the total watts you are using) x (your square footage). Example: You have an area of 10 sq. ft. – 50w x 10 s.f. = 500watts/sq.ft minimum or 50 watts x 10 s.f. = 500 watts/sq. ft. (optimal). Also, remember that fluorescent’s are weaker and emit less light than an HID. This means you will need 5 times the amount of wattage to equal the output of an HID. So, 30 watts of HID would equal 150 watts of fluorescent’s. This is why it is advised to provide a minimum of 30 watts per square foot for HID lights and aminimum of 150 watts per square foot for fluorescent’s.

    In more detail - How much light do I need?

    Chlorophyll & photosynthesis both peak at both ends of the visible light spectrum

    Technology has advanced so much in the last 15 years that we are constantly refining the process and updating what we know works best for growing. Current theory holds that the Minimum amount of lighting needed to sustain growth is around 2000 lumens per square foot. Mid range is around 5000 lumens per square foot. Optimal is 7000-7500, or higher, lumens per square foot.

    What if you want to determine how much light you need in watts? The general rule of thumb for providing light for an area is a minimum of 30 watts per square foot. 50 watts per square foot is optimal. You can determine the proper lighting for your area by using this formula: 30 watts (or 50) x ?(your) square feet. Example: You have an area of 10 sq. ft. – 30w x 10 s.f. = 300watts/sq.ft minimum or 50 watts x 10 s.f. = 500 watts/sq. ft. (optimal). Also, remember that fluorescent’s are weaker and emit less light than an HID. This means you will need 5 times the amount of wattage to equal the output of an HID. So, 30 watts of HID would equal 150 watts of fluorescent’s. This is why it is advised to provide a minimum of 30 watts per square foot for HID lights and a minimum of 150 watts per square foot for fluorescent’s.

    Theoritical Light Spectrum for indoor cannabis (Though LEDs are left out, they occupy a more efficient spectra than most HIDs)

    This is all important because the light intensity will directly affect the quality and yield of your crop. If you have less than optimal lighting your yield and potency will be reduced and buds will not develop as dense. This point can not be stressed enough. You must have the right amount of light for your space to grow high quality bud. The question is often asked, “can I have too MUCH light?“. Theoretically, yes you can, but in practicality you probably won’t. According to the law of diminishing returns, you could theoretically reach a point when your plants just couldn’t absorb any more light but it would be impractical and inefficient to do so. Heat from the lights would become a problem long before you ever reached that point. So use as many lights as you want, just control the heat.

    Experimentation is the only sure method to determine the best solution for each plant. If plants are not receiving enough light, they begin to grow tall and spindly as if stretching for the light and foliage becomes pale green. Or, if they need to be moved closer to the light, or given a longer light exposure period. Too much light may lead to bleaching of leaves and flowers, browning and shriveling. Leaves would become overly compact and curl under at the edges.

    PHOTOPERIOD (how long do I keep the lights on for?)
    Your plants should be started and taken through vegetative growth with a 24/7 or 18/6 light regimen. The reason for an 18/6 regimen is to give the plants a short dark period to breathe and to reduce your electric bill a little bit. Most plants thrive with at least 16 hours of light a day. Adjustments should be made according to individual plant requirements. For flowering 12/12 is the norm. Again, adjustments may need to be made. A minimum of 12 hours of darkness is required to trigger the flowering process.

    Light bleaching from being too close to the LEDs. Looks cool, but smokes like ass.

    Words of Caution
    Don’t burn your plants by getting them to close to the light(s).

    Fluorescents do not put out much heat and can be as close as one or two inches, but plants will grow into the light quickly, sometimes 2-3 inches a day, check them frequently for proper spacing.
    HID lights get much hotter and will need to be farther away. A good test is to put your hand between the light and the plant. If your hand gets too hot for comfort, the light is too close.
    LED lighting is only warm to the touch, but its soft intensity can be misleading. Keeping an LED grow light too close to plants can result in bleaching, but is easily fixed by keeping a 8″-24″ (depending on lamp wattage) distance between the tops of the plants and the LEDs.

    There are some common lights that may induce a seed to come up, but are worthless for growing purposes. These lights include; Any incandescent (regular) light bulb, halogen lights, black lights and heat lamps. Don’t waste your time trying to grow with these lights, you will only be disappointed.

    A Note on L.E.D. grow lights

    Pro-Grow 260 LED Grow Light

    The Pro-Grow 260 takes over for the 600w HSP!

    Growing indoors and employing L.E.D grow light technology is one of the newer methods employed in growing your plants effectively indoors. This form of light is completely different than the standard (HID) high-pressure sodium and (MH) Metal Halide variety of grow lamps in many respects.

    Plants convert light energy into plant energy via photosynthesis. There are two primary compounds that achieve photosynthesis: Chlorophyll A, and Chlorophyll B. These compounds absorb blue and red light, while nearly all other spectra are reflected away from the plant and into the nether. There is a term called the “absorption peak” which is the point at which Chlorophyll converts light energy into plant energy the most efficiently. These absorption rises can be measured in units called nanometers (nm).

    L.E.D’s (LED grow lights) are light sources that emit narrow wavelengths of light, and can be tailored to nearly any nm that you as a grower desire. By using L.E.D’s at the same nm as each of the absorption points for Chlorophyll, high-quality systems (like the Pro-Grow series we use) convert light energy into plant energy much effectively than HIDs, a Pro-Grow 180 LED lamp is easily comparable to a 400 watt HPS.

    High Intensity Discharge lights, like HPS and Metal Halide, emit full spectrum’s of light (most of which is unused by plants in the form of heat), quality LEDs (like the Pro-Grow line), emit only the spectra that plants require which results in much higher efficiency in terms of growth per wattage used. By using the ideal ratio of L.E.D’s, 95% – 100% of the light generated by the units is used for photosynthesis. The bottom line is that your plants will utilize less overall wattage and produce the same yields as under HID lamps.
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  4. #4
    420 Member RollinKron's Avatar
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    So would my 4ftx4ft 16sq feet under a 600w baddass bulb hps 90,000 lumens be sufficent, and how much could I expect from two indica dominant strains in total. I was going to do 1 plant per sqft