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how far should 4 42 watt cfls be for seedling


New Member
I have 1.7 square feet in my grow room (1'4"x1'4"x3'11" is the size. gl40 growlab). 4 42 watt cfl in a 10" clamp on reflector. Growing in 16 oz. Plastic cup. I might start with 1 gallon. Should I use all 4 bulbs to start with? And how many inches away should they be from before and after it breaks through the coco coir medium. only 1 plant


420 Member
Re: how far should 4 42 watt cfls be for seedling.

With a SMALL seedling 1-2 bulbs is fine, no more than 6" away, preferably about 3" away. But no closer than 1".

After 1-2 weeks, depending how fast they grow, I'd use all bulbs, for Veg you can get by, but I would suggest adding a few for Flowering.
But more bulbs is always better with CFLs.

I suggest transplanting from the cup into the final pot when they're ready. 3 gallon minimum, 5 gallon preferred. Remember for every 1 gallon it will support about 12" of plant height. If you transplant a larger soil mass, the risks of the soil breaking apart and ripping your roots apart increase.

Topping your plant around 4-6 weeks, and training it to grow flat will help you get the best efficiency from your CFLs.


New Member
Re: how far should 4 42 watt cfls be for seedling.

I have it 2 bulbs on, 4" away, and it sprouted Only a day and a half later from putting it in 16 oz cup. Thanks for the help guys.


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