how much light?

Discussion in 'Newbie Central' started by Harry Potter, Oct 7, 2009.

  1.  
    Harry Potter

    Harry Potter Member

    How much light does a pot plant need or want, to grow the healthiest plant?
  2.  
    GrizzlyAdams

    GrizzlyAdams Well-Known Member

    Do some more reading my friend. To save you this one, MJ needs a minimum of 3,000 lumens per square foot to grow. They are happy with 4-6k per square foot, more doesn't hurt but higher than 6k you're prob gonna be wasting power in heat and light that isn't going to be a positive return for your grow.
  3.  
    DoeEyed

    DoeEyed Well-Known Member

    3000 lumens per square foot minimum, 5000 lumens per square foot recomended.:peace:
    Here's a sample chart to help you:
    23w CFL = 1600 lumens = 69.6 lumens/watt
    30w CFL = 2000 lumens = 66.7 lumens/watt
    40w CFL = 2600 lumens = 66.3 lumens/watt
    150w HPS = 14000 lumens = 93.3 lumens/watt
    250w HPS = 28000 lumens = 112 lumens/watt
    400w HPS = 50000 lumens = 125 lumens/watt
    600w HPS = 90000 lumens = 150 lumens/watt
  4.  
    Harry Potter

    Harry Potter Member

    It looks to me like your saying about 3 30w cfl's will be the right amount for a plant taking up an area of about 2 sq feet in plan view. Do you have to add some for the sides of the plant. Do you take the area of all the green surface. like the average circumference times the height of plant plus area of plan view.
  5.  
    DoeEyed

    DoeEyed Well-Known Member

    Sounds about right - but keep in mind, the 3000 lumens per sq ft is the minimum amount you want. More is better.:peace:
  6.  
    GrizzlyAdams

    GrizzlyAdams Well-Known Member

    I'd shoot for 4-5k. Thats the range i've seen for a happiness increase. 3k going to 4,750 there is a clear difference. 5k-6.5k? Meh, not as noticeable. A thing to remember is HIDs penetrate the canopy of plants well, CFLs do not do as good of a job. Supplemental lighting below the canopy ain't a bad idea but keep it supplemental. You don't want to confuse the plant and make it think the sun is behind its ass. Keep the bulk of the light above ;)
  7.  
    Illegal Smile

    Illegal Smile Guest

    A few additions: lumens per sq ft means just that. It is not how many lumens are emitted, it is how many reach the target area. So for starters you have to divide the total lumens by the number of sq ft. Then, you have to do an honest estimate of how much light is realling falling on the grow area. Is any at all hitting floors and walls? Of course it is, and 3000 per sq ft minimum doesn't include what is lost. So you really ought to shoot for 5000 lumens generated for every sq ft of grow area, and regard that as a minimum. You can get by with less in early veg, and you really should have more in flower. Both in the correct spectrum ratio as well.
  8.  
    Jaiixd

    Jaiixd Member

    yes lumens are what counts...lets say i have a pc grow case (which I do) its about 1 1/2 foot wide and about 1 1/2 foot tall...i have 3 60 watt 1600 lumen cfls - so 3 x 1600 = 4800 = perfect :) healthy grow...i recommend lowes or walmart for the cfls...however lowes doesnt offer many cfl with high lumens (or atleast mine didnt) the highest i found was 1600 but i tripled em up and it works fine :) good luck bro
  9.  
    Nike617

    Nike617 Well-Known Member

    if you want a good grow you want atleast 6,000 lumes per sq foot
  10.  
    Nike617

    Nike617 Well-Known Member

    get rid of the cfls get something better you need bigger lights dude
  11.  
    Jaiixd

    Jaiixd Member

    4800 Lumens in my pc case is working great I guess it just depends if you are doing more than a 1 plant you def need something dif tho.

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