Black lights

Discussion in 'Growing Marijuana Indoors' started by keepsmokin, Apr 29, 2002.

  1. my science teacher said that plants grow best in the lower end of the light spectrum following ROYGBIV the last two letters representing indigo and violet and said that black lights will increase photosynthesis by having more indigo and violet light

    Is this true for marijuana
  2. during one of my indoor grows I was under the same impressions so along with two flouros, I had one growlux grow light and a black light...never hurt the plant..but I had no way of rweferring to another plants growth so I cant say that it helped at all.
  3. ok just seeing if he was right
  4. on the other that I think about it, I believe what a black light emits is UV rays. Too much of this will harm a plant, so if you do use one id suggest use it in combination with several other normal flouros and make sure to keep the black light somewhat far away from the leaves
  5. Black lights are mainly UV radiation/light,,and will provide nothing for the grow that you expect. Although the teacher was not entirely incorrect,,as that part of the spectrum is included in the arc of a MH,and the gas mix,and coatings in plant/aquarium flourescents.

  6. I read in one of Ed Rosenthal's books that UV increases the THC levels, but can fry a sprout and cause stretching. I also read about using black light during the dark cycle. I don't know many people who bother though since the only black lights I've seen are 15 watts. Any use of a black light for growing is basicly experimental IMO.

  7. where did you see 15 watt black lights?
  8. Home Depot, Lowes, and Wal-mart carry them.

  9. That makes sence.. since MJ creates THC to protect the plant from UV. You want lights that are high blue&violet or red&orange, anything on the two extremes of the light spectrum.

  10. Ahem..THC to protect the plant from's offense..but who told you that one?

    And on the 420th day,,the Gods gave Metal Halide,and High Pressure Sodium,,,,,and said...Grow Well My Sons,for we have shown you the lights....

    Black lights for UV....been there...done that,,,what did I learn?..When you want more potency from your buds,,,grow a better strain,,use CO2,,and be the best mother nature you can be...


  11. THC plant resin is created by the plant in order to protect itself from UV rad. I've read this in more then one place..
  12. I'm curious,,,do you have a source,or link? In all the grow books i have studied,,I have not run into that claim...

  13. im not saying uv makes more thc just that it speeds up photosynthesis

  14. I'm still curious about this......

  15. wow good article yea it says THC protects the plant

  16. i have a question...what if i used a 20 watt black light, a 20 watt blue light, and a 20 watt red light? thats the kinda lights i got right now, and im just lookin for some average personal bud here, would this be ok?
  17. Lighting,

    60 watts in total will flower a space of about 4inches by 3inches which is about 1 sq ft of space,,,,, I suggest anyone wanting to grow the "Good Herb" and actually get some decent bud start off with a small HPS such as a 150HPS security light or even a 250watt HPS.

    Floro lighting isnt to bad if your just vegging the plants, as they emit very little heat and you can keep the bulbs close to the top of the plant, though once flowering is started they do not give off the lumens needed to make tight crystally bud as wanted by most growers.

    good luck,

  18. if you had a chioce between a 20 watt yellow, red, blue, green, or a black light to grow pot which one would be best suited

    the low wattage cause a power spike would be noticed(living at home)
  19. look man, i already said it would be hard to get more lights, other wise id go for a 250 hps, but i live at home and this is what i have right now since i have no job (yet) and no money. You said it would flower a square foot of growing space, i have a 2wx2lx4d space and only 2 plants that i just started today. could i get any crop at all with this or would it be better to wait until i can get the hps or some floros or something?

  20. Now your on the right track...why even start when you don't have the means to do the plants justice.You would only be dissappointed.......peace


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