How far do you put your lights above the plants?

Discussion in 'General Marijuana Growing' started by just a medicator, Jan 22, 2014.

  1.  
    just a medicator

    just a medicator Active Member

    I've got 3 600W air-cooled HPS lights. I've been told 18-24 inches. Right now I have them at 24inches above. What do you think? Go 18? or just try 24 out, see how the plants react and how temps are from the distance then adjust if necessary? I previously had them about 30-32 inches above the plants and at the plants height the temperature was getting up to 78F.
  2.  
    AimAim

    AimAim Well-Known Member

    six (6) inches if you are running air through them.
  3.  
    joe macclennan

    joe macclennan Well-Known Member

    Use a IR thermometer 20$ and check the tops. this'll tell you exactly how close to run em.

    Don't go over 88 F for long and you'll be good.


    those things are awesome around a grow imo
  4.  
    AimAim

    AimAim Well-Known Member

    Otherwise you will and can burn their nuts.
  5.  
    colonuggs

    colonuggs Well-Known Member

    use the back of your hand...if its hot to your hand.... its hot to the plant... I can leave plant tops under 1000s 12 inches from the bulb
  6.  
    just a medicator

    just a medicator Active Member

    Thanks. Awesome idea, never would've thought of using one of those things. I'ma order one of those off amazon right now!
  7.  
    KumeStorm

    KumeStorm Active Member

    the closer the better, as long as it stays cool enough (optimum temp is 74-76F)in the tent and all the plants are getting great light then youll get great bud...i have 2 thermometers tied to my lights with the sensors hanging down to the same level as the tops of my plants, that way i know exactly how hot my plants are getting, if you have good cooled hoods and a cool room, you can put the lights almost touching the plants, some hoods are so cool you can touch the glass, which alows them to be so close :) it prevents the plants from stretching and makes it very dense buds..the further away they are the more light and airy the bud is, if you dont have enough watts per square inch...this is probably more than you want to know..but hey its informational :)
  8.  
    KumeStorm

    KumeStorm Active Member

    and you can safely be between 65 and 85 for several hours, but the 70s is the sweet spot
  9.  
    joe macclennan

    joe macclennan Well-Known Member

    85 w/co2 ,,,,
  10.  
    KumeStorm

    KumeStorm Active Member

    with co2 you might be able to run that hot all the time for all the light cycle..but thats why i said a few hours, not a full light cycle, and plants will be fine in 85, its a bit hot but it wont kill them, some of the best outdoor weed you can find in the US is around where i live, and it gets to and stays 90-105f for several weeks during every grow season and the bud is amazing up here :)
  11.  
    budleydoright

    budleydoright Well-Known Member

    18-24 for 600 and 24-36 for 1ks. Closer isn't always better. You buy a bigger bulb for more coverage. A 1k doesn't get much spread 12" over the tops.
    If you have a need to keep your lighting fixtures close to the tops stick with floros! Even my water cooled 1ks performed better at 30".
  12.  
    bigsteve

    bigsteve Well-Known Member

    It's a tradeoff, eh? The closer to the light the faster the plant grows. Get the greenery too close to the light and your plant will burn. Pot plants are about as sensitive to heat as a human hand. So put your hand over the top of the plant. If your hand is uncomfortably warm you are too close to the light. BigSteve.
  13.  
    budleydoright

    budleydoright Well-Known Member

    My experience has been that the buds develop better, the pistals are longer when the light is 30-36" away. I observed this while my watercooled 1k was 12-18" away from the tops and the plants in the cheap seats 24-36" away were more developed, healthier and had more density. I dunno, maybe all the big rooms that have their 1ks 3-4ft above the tops are wrong.
  14.  
    colonuggs

    colonuggs Well-Known Member

    In flower... I can go 12 inches away with 1000s bare bulb...no heat meter needed...depends on how your strain reacts

    [​IMG]
  15.  
    Aeroknow

    Aeroknow Active Member

    This is the best answer in this thread. Don't forget about light spread. Buy a light meter(they're cheap). Just don't try and spread those lights to wide. 600w=3x3
    1000w=4x4
  16.  
    Ninja Mechanics

    Ninja Mechanics Member

    Rule of thumb for me is generally two feet at all times. Veg, flower, clones and seedlings. I grow all naturally and have found through experience that they prefer a light source to not be much closer than around 1.5 feet. It all depends greatly on the source of light. HID's need to be at least two feet away. T5's can be placed closer but keeping a consistent distance of 1.5 feet is crucial in my experience.
    Everyone runs a different set up, experiment a bit and note the differences. You may find you can place your lights closer than say I would in my grow. :)
  17.  
    Ninja Mechanics

    Ninja Mechanics Member

    I disagree that the closer the better. This is highly dependent upon your growing method and state of a given plant. This will never be the case in everybody's grow. My plants don't like being any closer than about 18 inches from a given light source. Even T5's which can be placed very close without heating up the leaves to much, the plant metabolism is a better gauge of where to place your light distance. All natural plants like I grow prefer a distance of about two feet at all times. Any farther and growth is slowed, any closer and growth is slowed plus various deficiencies start to show up due to the increase in metabolic processes. Liquid fed synthetic grow styles can produce plants that don't give a hoot how far the plant and light are from each other as long as heat is not an issue. Mainly because your force feeding the plant, the plant is not able to decide what it needs and wants, it has no choice, therefore metabolism is artificially maxed out. Given a choice between synthetically produced herb and all naturally produced herb, I choose all natural every single time. It smokes better, tastes better and possess a much more potent, clean riding high that lasts a loooong time compared to synthetic herb.
    I have seen and produced myself some of the biggest, densest, most potent resin packed buds with light distances of 3 feet or more away from the plants. Its a matter of how established the plant is and how healthy the plant is and was while growing during the veg and flower period. Ill argue this fact all day long.
  18.  
    budleydoright

    budleydoright Well-Known Member

    Bare bulb. no reflector, halide is a whole different story. I'm specifically talking a 1k hps in my case.
  19.  
    LordRalh3

    LordRalh3 Active Member

    You cannot use inches or distance. Everyones airflow, ambient temps, bulb quality type age, wattage etc are different. Put your hand under the light. If it burns you its too close. If you cant feel the heat your too far.
  20.  
    Ninja Mechanics

    Ninja Mechanics Member

    I don't agree. Distance is a great way to measure how far away to place your lights. I agree that using your hand is a very effective method of judging when it is to hot and what is acceptable. I do this always, daily, every grower should practice this no doubt. If its uncomfortable for me, its uncomfortable for the plants in most cases indoors. However, there is a general distance that is acceptable for me when it comes to indoor lighting and all natural growing styles, that distance is about two feet in general. I grow in tents and rooms, large plants and small plants, using several different sources of light that emit very different spectrum's and heat intensity. Rule of thumb for my plants to be comfortable in my experience is around two feet, sometimes further. I see steady vigorous growth with less hiccups along the way, that's my opinion based on experience, not my opinion based on my thoughts. Efficiency is the name of the game, I strive to achieve maximum efficiency and quality in all aspect of growth.

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