Hey all, I’ve an air cooled 600watt hps light for flowering. How close is too close?
Looking at the lighting charts I find 8" max. Yet the sweet spot chart says 12". Other forum comments suggest 18".
I’m trying to kill some bag seed in order to find out… Lights at 6" for 3 cycles didn’t show any neg. Effects. They’re at 9" now. I’m vegging some feminized ilgm seeds and want to dial things in before they flower.
Being a 600 watt hps light it will heat up as it stays on longer so my opinion is hang it about 8" above plants, and vegitative stage you should try to invest in a mh bulb they put off blue spectrum which is more vital for vegitative growth. Any ways you can beat results would come from about 8-10 from plant canopy, but you want a oscillating fan with different fan speeds to keep the canopy of the plant cool and not to hot, also will help keep lights a little cooler, and plants will love the breeze, the wind will act as a positive stress on the root structure and stock
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One of the rules I follow is that if you can comfortably put the back of your hand if front of the light and leave it there, it should be a good distance for the light from the canopy of the plant. The distance varies on the wattage of the bulb and type of bulb (HPS and LED are hotter than fluorescent generally). Best to watch the leaves very closely at first and adjust the light as required. Flowering will use more power and it is surprising how close the lights can get without plant harm. Hope this helps you. Jerry
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That is a good rule of thumb for light distance I don’t know why I didn’t think of saying that lol, and i use the palm but same thing lol, thanks Jerry, glad you posted that in here, spaces out and didn’t think of that
as Jerry said you should be able to comfortably hold the back of your hand at top of canopy also depends on how big foot print you want too
Sry, I failed to mention that temps with an oscillating fan and vent fan(pulling thru light) keep my 3x9 area under 75 deg.f. All vegging is under led/ cfls. It’s been a decade since I last grew…a brother with t cell lymphoma has renewed my interest.
Thanks for the advice.
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Between 18-24" would be best balance between sweet spot and foot print
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Still doesn’t change what I said. The room can be cool BUT if you have the light too close, it will still burn the plant. Another thing not to get caught into is what the lighting charts say. Every light is different and needs to be treated as such. My LED does not perform as the charts said. I used it blindly on a grow and lost three plants before I moved it out farther and everything worked well. Good luck on your grow. Jerry
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just a thought ,i haven’t tried it yet .but if you get a cheep point and aim thermometer then hang or place a dark paper “small” under the light at the tops of your plants then check the temp …if the paper shows high temps then your plants are at high temp even if the room is cool. i hope this makes sense . the paper absorbs the heat same as the plant
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Living this from my grow now…hoping to save 2 out of the 4 plants. What I was stunned about was the damage occured overnight with no hint.