1. We are currently experiencing issues with viewing and uploading images, our team is working on the issue.
    Dismiss Notice

how many watt do you need per plant using cfl light bulbs and how far away do you?

Discussion in 'Newbie Central' started by PotOfCannabis, May 6, 2012.


    PotOfCannabis Member

    okay so how much cfl watt lightage do you use per plant for a good growth like 4 23w or 3 30 wats or 2 65 watts for 6 plants and how far away do i put light from the plants of the wattage for the cfl light?

    aCiDjEsUs Well-Known Member

    Plants use mostly red and blue light. Yellow and green light is of little use to them, so light that is emitted in these spectrums is wasted energy. Most of the light emitted by HPS lamps is in the yellow spectrum. Only a small amount of the emitted light is is in the orange or red spectrums, which plants use efficiently. Warm white fluorescents (2700 Kelvin) emit a greater portion in the red and orange sectors. Although fluorescents produce only about 75% of the light per watt that the HPS does, the amount of light usable by the plant is equal or probably higher with the fluorescents. You may wish to experiment to see if adding a single cool white CFL to replace one warm white results in shorter, stouter stems and more vigorous growth. The reasoning is that warm whites don't emit much blue light, which the plants use for photosynthesis and to regulate their growth. The cool white bulb supplies the blue light.
    My call for your unit would be to use several (three to five) CFLs with a total input of between 120-160 watts. Although the 150 watt HPS is a bit more efficient that the CFLs in total output, watt for watt the fluorescents provide as much useful light as the HPS lamp. Heat is another consideration. The HPS runs much hotter and emits more heat than the fluoescents.
    Make sure to use reflective material around the garden so that any light escaping the garden is reflected back to the plants. Any light that doesn't get to the plant leaves is wasted.
    42 watt average $ 9 to $10.00 each
    65 watts, = $19.99 average price ($16.95 now at Lowes and Home Depot)
    85 Watt, average $29.00 each, can be found for $24.95 on Internet
    105 watt average $34.95 to $38.99 each 105s come in Tube type and Spiral
    Or Look for Clamp Reflectors and Bulbs together:
    CFLs come in 15, 26, 42, 65, 85 and 105 watts and recently last year, even larger wattages. The 26s and smaller are not as efficient to me. 26s to 85s do not put out any noticable heat unless you use a lot of them.. The 105s do put out some heat, but not as much as HID lights. I can touch and hold a burning 65 or 85 watt bulb. The 42's are about $9 each. 65 watts are abut $17 to $20 each, 85s are $30 each, 105s are $39 to $42 each, average is $40 each for 105s. A CFL needs a reflector, like a hood. I like the $10 heavy duty clamp reflectors at Lowes, Home Depot or Walmart. They also offer a cheaper $8 reflector but it is smaller and flimsey.
    With CFLs, you need the DUAL SPECTRUM, red and blue spectrums. That does not refer to the color of the bulb that you see. It refers to the kind of rays, like UVA or UVB, or the color temp, called kevins. CFLS come in 2700 kevins, 3000, 4100, 5100, and 6500. 2700k is for BLOOM OR FLOWERING , 6500k is the VEG Spectrum. The others are "MID" spectrums or in between. IF you use the MID-range bulbs (4100) then also use the 6500 and 2700s. In outdoors, the sun produces different rays in the spring (VEG Rays called Blue) and late summer for Bloom spectrum, the RED spectrum. The sun also produces green, and orange rays, but plants do not use them. (see more below)
    CFLs are new on the scene, in 2006 the biggest made was 65 watts. When we talk about CFL watts, we are talking about the actually electricity used, NOT the equivalant. For example, a 15 watt CFL bulb puts out 60 watts.
    Spiral and Tube type CLFS emit LIGHT FROM THE SIDES, NOT THE ENDS OR TIPS.
    YOU CAN GET SPIRAL CFLS (15, 26, 42, 65, 85) AND TUBE TYPE CFLS 105s.
    How much light is needed for growing? Depends on the size of plant you are trying to grow. I'll try to answer this "in general" instead of being specific to one size plant. Light seen and perceived with the human eye is measured in Lumens. There is an ideal amount of lumens for growing and a minimum amount of required lumens. The very minimum amount of light required for smaller sized plants grown is around 3000 lumens per square foot. Let me put emphasis on "minimum amount" of light. However, that's not 100% exactly accurate, since although you may have a 10,000 lumen light, the amount of light that reaches the plant varies with the distance between the light and plants, and the reflectivity of the grow area. The ideal amount is somewhere around 7000-10,000 lumens per square foot for average sized plants. As long as the plants do not show burn, as much light can be used as you want to use. (Note, the sun produces about 10,000 lumens per square foot, on a sunny mid summer day). Contracy to "talk" you CAN have too much light.
    Determining lumens for your grow area: First determine the square footage of your area (example in a 4 foot by 4 foot area, there is 16 square feet, 2 by 2 feet is 4 Sq ft. ) If you have a 1000 Watt High Pressure Sodium Light Bulb, that produces approximately 107,000 lumens. Divide this by 16 (your square footage) 107,000 divided by 16 = 6687 lumens per square foot. So just divide the total amount of Lumens, by the total amount of square feet, and that's your lumens per square foot.
    How far away from my plants do the lights go? The lights in your grow room should be as close as possible to the plants without burning them. There is no such thing as too much light, unless there is overly sufficient heat to dry out and burn the leaves. A good rule is to put your hand under the light, if its too hot for your hand, chances are that the plants will be too hot too, so move the light up until your hand feels more comfortable. For seedlings or sprouts, I keep them a little further away from the light, because they are very susceptible to burning and drying out, at these young stages.
    How do I decide which lights to use? Efficiency is very important when choosing a type of light. The wattage is not the most important thing, different types of light produce different amounts of lumens per watt. For example, a 300 watt incandescent will produce about 5100 lumens. (not that you can grow with incandescent bulbs) While a 300 watt Metal Halide (just an example, they do not come in 300 watts), will produce 27,000 lumens. Obviously far more efficient for growing, while still using the same amount of electricity.
    Approximate light production: Incandescents: 17 lumens/watt Mercury vapor: 45-50 lumens/watt Fluorescents: 60-70 lumens/watt Metal halide: 90 lumens/watt High pressure sodium: 107 lumens/watt
    Incandescent lights: Incandescent bulbs are the most popular type of lights in the world. They may come advertised as incandescent, tungsten, quartz, halogen, or simply standard. The important thing about incandescent bulbs when it come to growing is simply this: they suck. Using incandescent bulbs to grow plants is like trying to flag down the Space Challenger with a burnt out match! You can do it, but it won't work. There are some incandescents which are sold as "grow lights." They usually have a blue coating and usually come in 60W and 120W sizes. While they may seem like a good choice to new growers, they are next to useless; they produce some light at a usable spectrum, but only have about a 5% efficiency and generate more heat than usable light. Most of us have these in our homes right now. Don't use them for growing, instead opt for a Compact Fluorescent, CFL, as a cheaper but more efficient alternative.
    Fluorescent lights: Fluorescents are far more useful than incandescents. They are efficient enough, and much less expensive than HID (High Intensity Discharge) lights. Compact fluorescent tubes, (commonly called CFLs) are popular with growers because of their good output to size ratio. Compared to standard 4 foot tubes, CFLs are smaller, more easily moved, and more can fit into a given small area. CFLs are good for small grows on a tight budget, and for novice growers, since they do not require any special sort of wiring or understanding of the necessary bulbs for a given fixture, and the small wattage ones (23, 42 and 65) are very widely available. Fluorescent lights come in many different Kelvin (spectrum or color) ratings; often the spectrums are labeled on packaging as being 'cool white' or 'warm white.' Cool white is more blue, and is good for the vegetative stages of growth. The bulbs are ultra white. Warm white light is more reddish in spectrum, and is best for the flowering stage. The bulbs are almost cream colored.
    Color rating - Measured in Kelvin (K). The higher the number, the more bluish the light. 4000K-7000K is mostly on the blue side of the spectrum for Vegging or GROWING, while 3000K and under goes from a white spectrum, to a redder spectrum and is best for BLOOMING or FLOWERING.
    High Intensity Discharge (HID) Lighting Systems:
    Mercury Vapor (MV) Mercury vapor lights are not the most efficient light for growing. They are very bright, and relatively cheap. They do emit light at the wavelengths necessary to support your plants growth, but not nearly as good as a MH or HPS light. Much of the light emitted by MV lights is bluish-white. Street lighting is what most MV lighting is used for.
    Metal Halide (MH) Metal halide lighting systems are optimal for use in the vegetative phase of growing. They emit mostly blue light, which encourages vigorous growth of foliage. They are very efficient, but can get rather expensive to start with; fluorescents may seem more appealing because of their lower price, and they are not much different when compared on a lumen-to-lumen cost level. These lights can be used through-out the grow, but leave a lot to be desired in the BLOOM stage.
    High Pressure Sodium (HPS) High pressure sodium lights emit mostly orange, yellow, and red spectrum light, which is perfect for the flowering stage of the plants growth. They are (in my opinion) the most efficient type of light available for any application if you are not on a budget and can vent the grow area for heat. HPS lights can be used through-out the entire grow. They produce more dense and usually larger flowers or fruit than any other light. HPS lights are generally a little more expensive than MH systems of similar wattage. They are more commonly used by experienced commercial growers because of their ability to produce tighter denser flowers, higher lumen-output-per-watt, and will produce from start to finish.
    Just like everything else, available grow lights are evolving. Remember how the sun produces 10,000 lumens per square foot in the mid-summer. Well, today there are CFLs that can actually duplicate those lumens. If you can not grow under the sun, then bring the sun inside. Yes, you can have 20,000 lumens covering the entire grow space with the new 105 watt per bulb CFLs. Three of these bulbs in the proper reflector actually yields 20,000 lumens.
    Low heat, energy efficient light bulbs . Available in blue (vegetative) and red (flowering) spectrums. I like being able to move the CFLS around, and lower them down in between the plants, the clamp- reflectors are just $ 8 to $10 each. Lowes, Walmart, Home Depot:
    and get one of these extensions: and if you want to add two 42 watt lights to a reflector, you get a Y spliter.
    This pic shows both COOL WHITE and WARM WHITE, or high and low kevin bulbs:
    One of many mistakes I have made over the years, is I wish I had labeled or dated my bulbs.
    I have some 65 and 85 watt bulbs, and they have seen 6 GROWS. I wish I knew how to distinguish them from the new ones.
    I highly urge everyone to date-label your bulbs.

    When given the choice of only one light, most marijuana growers will choose an hps grow light over mh, because hps lights are more efficient (larger harvest). You can't use a standard high pressure sodium bulb in a metal halide fixture, but you can use a metal halide bulb in a high pressure sodium fixture of the same wattage. There are special hps bulbs that can be used in a mh fixture and vice-versa. But these conversion bulbs cost about double the price of a standard bulb. A 250 watt fixture will supply enough light to cover a 2.5 foot by 2.5 foot grow area. (6 plants or less) A 400 watt fixture will supply enough light to cover a 4 foot by 4 foot grow area. (12 plants or less) A 600 watt fixture will supply enough light to cover a 5 foot by 5 foot grow area. (18 plants or less) A 1000 watt fixture will supply enough light to cover a 6.5 foot by 6.5 foot grow area. (30 plants or less)
    IF you break a CFL
    IF YOU BREAK A BULB... 1) Open a window before cleaning up, and turn off any forced-air heating or air conditioning.
    2) Instead of sweeping or vacuuming, which can spread the mercury around, scoop up the glass fragments and powder. Use sticky tape to pick up remaining glass fragments or powder. Wipe the area clean with a damp paper towel or wet wipes.
    3) Dispose of the broken bulb through your local household hazardous waste program or recycling program. If that service is unavailable in your area, place all clean-up materials in a trash container outside the building.
    4) Wash your hands after cleaning up.
    5) If vacuuming is needed afterwards, when all visible materials have been removed, vacuum the area and dispose of the vacuum bag in a sealed plastic bag. For the next few times you vacuum, turn off any forced-air heating or air conditioning and open a window before doing so."

    montanachadly Active Member

    For 6 plants your gonnna need quite a few smaller ones or some bigger ones i start all my plants out under cfls until there like 6 to 8 inches tall with 5 sets of alternating branches then i move them under a t5 or a mh. when the plants are small one 26 watt is enough for one plant starting out when they get more leaves on them you will want to add more cfls a bare minimum is 4 to 6 23w cfls when vegging per plant over 12 inches. on the top and the sides the cfls should be placed within an inch or two. I have found that the cfls are nice to start the plants and get them going cause you can get the light closer than hid lights and you can put them in smaller places which means more plants but if you want to grow 6 plants with cfls you must be on a budget thats the reason for the cfls buy yourself a 55 gallon tote from walmart and set it up to veg. The cfls arent practical for flowering IMO you need to look into a HPS to get desirable results.

    bbqtony Member

    here is a pic of my setup using CFLs.. :) my 1st grow..getting ready to start my second in a 5x8 room
    puertorrican diesel

    puertorrican diesel Well-Known Member

    Hey bro i updated my lights and set up,i used to have only (2) 68 watts bulbs at 6500k., and only 3000 lumens between the 2 bulbs now i upgraded to 285 actual watts and 1000 watts equivalent ., and 17,100 lumens at 2700k i have more lights but i need more spliters. , But when i go and buy more spliters and extencions cords and i put all the lights that i bout im gonna have 386 actual watts equivalent to 1600 watts and in lumens will be 26,800 thousand lumens at 2700k.. what do u think now?

Share This Page