I should move the light to 3" away since 36/2 = 18 and 54/3 = 18. Please help me

A customer has a question and I hope we can get some opinions on it, thanks

Hello, it says in your 8 steps to germinate guide that once they have soaked for 24hours in water to then put them in the soil and under a 36w cfl light 2" away. I have a 54w cfl from tobacco grows and other prior things I’ve grown, I am going to use that. I am wondering if I should move the light to 3" away since 36/2 = 18 and 54/3 = 18. Let me know if that’s perfect or if I should just keep it at 2" for some specific reason. This is my first time growing cannabis and it seems to be a LOT pickier than tobacco and many other things as well as coming with a heftier seed price so I’m not trying to mess up with anything. I’ll take all the help I can get, I went all out on my purchases and I’ve read your ILGM grow bible about 4 times now and will continue to use it as a guide. Thank you for making it free. I look forward to hearing from you ASAP. Thank you, Nathan R.

You won’t see any practical difference by moving it one inch up. You should be fine with the CFL’s as close as you can get them. They will not work for growing decent plants with any kind of yield so if you haven’t already; start looking for a good veg and flower light.

If you want to get anyone’s attention just put the @ sign in front of it like this: @dbrn32

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I agree with this^.

I’m not aware of any conversion factors similar to that. There’s the law of inverse square, which I’m not prepared or qualified to break down any level. I know my dome is 7” tall, and with seedlings taking up a couple of inches of that, I’ve run 24 watt fluorescent tubes a couple inches above my dome without issues. Generally speaking when considering same types of light, more power=more light.

So I don’t see there being a big difference between 2 and 3 inches. But you could also be running that light 2-3x above that for seedlings. Where you would see a pretty big difference in light intensity levels. When in doubt, I start on higher end and watch for plants to stretch. If I see stretch I lower light. Easy peasy!


Okay, thank you.