Amount of CFLs needed for 4'x4' grow space

Qmoney

New Member
How many watts needed per sq ft for CFLs
I have 8 plants and 700 watts in a 4x4 space
Also how close should they be and should I use reflectors or just plugs or a mix?
 
How many watts needed per sq ft for CFLs
I have 8 plants and 700 watts in a 4x4 space
Also how close should they be and should I use reflectors or just plugs or a mix?



5 zone CFL lamp w/ T5 sunblaster
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My grow journal

Mother of Berries - M.O.B. - Maine Strain

Your probably gonna need approx 40 CFL bulbs at 2700k spec. For that many plants. The pic I showed you above is for ONE plant.
 
How many watts needed per sq ft for CFLs
I have 8 plants and 700 watts in a 4x4 space

Enough that you'd end up using less electricity with HPS lighting and most likely see cooler temperatures, too (especially since it's a lot easier to run a duct to/from an air-cooled 600-watt HPS setup than it would be to build air-cooled reflectors for a gaggle of individual CFL bulbs. A 600-watt HPS might be enough for your space, depending on the footprint of the light (it may or may not be the same shape as your square-footprint grow room) and the strain(s) you grow (pure sativas would probably benefit from another couple hundred watts or more).

That's 16 ft.² you need to adequately illuminate. Traditionally, with HID lighting, a minimum of 30 watts per ft.² for vegetative and a minimum of 50 watts per ft.² for flowering was recommended. Again, that would be for indicas and hybrids with a significant percentage of indica genes, not sativas. CFL bulbs just aren't as efficient. Therefore, you'd want to increase those recommendations by a factor of... 1.5x?

You can sort of improve on their efficiency (in practical terms) by interspersing a large number of bulbs all through your canopy, hand-crafting individual CFL reflectors out of soda pop cans or something similar, keeping the bulbs as close to the plants as possible (necessitating at least daily repositioning of all the bulbs), and always remembering that the vast majority of the CFL bulbs' output comes from the "sides," NOT the end - which means that, for best results, the bulbs need to be positioned sideways/horizontal directly above the plants (again, with reflectors to direct the other 50% of the output towards the plants). This may not be convenient if one wishes to use a couple dozen of those "Y" socket adapters - but it is best. And, since you're paying for the same amount of electricity whether all of the light produced by it lands on your plants' leaves or not, lol...

Also how close should they be and should I use reflectors or just plugs or a mix?

See above. If you're speaking in regards to those little 23-watt or 26-watt CFL bulbs, within an inch of any plant large enough to not be called a sprout, lol. Their output is weak to begin with, no matter what you do some of the light will end up getting blocked by parts of the bulb, and the inverse square law of lighting states that the intensity of its output decreases... Err... The decrease is the square of the distance (IOW, double the distance and you're only giving the plant 25% of the illumination). These - along with the fact that, to produce the same amount of light requires more watts, which means more heat, the ability to cool HID lighting via air-cooled reflector setups, the sharp decrease in complexity (hang ONE reflector, raise when necessary vs. hang MANY bulbs, reposition at least once per day)... If you are wishing to fully illuminate a 16 ft.² space, you would be better off going with HID - regardless of whether you are growing one or two sativas or 100 lollipop indicas in 2-liter pop bottles. CAN you have a decent harvest with CFLs? Of course! But you'd spend less in electricity each month, have a larger (and quite possibly more dense) harvest, or both with a proper amount of HID watts. IMHO.

I started growing way back in the day with 4' fluorescent tubes. Briefly tried mercury vapor (second best way I have found to kill a cannabis plant - although dumping way too much General Hydroponics Rare Earth silicon supplement was slightly faster, since I returned the next morning to discover all the leaves on the floor :lol: ). Then metal halide. When HPS became more available, I started using them. I even have some LED experience now, lol. So, basically, when CFLs came out I experimented with them, too. I'll still use them for seedlings, for supplemental lighting to decrease shady spots, or for very small grows (they can be quite handy for one plant, and not unduly inefficient for that purpose). But for grow rooms of any real size, I'd not bother. Unless I really, really wanted to start a grow and only had enough money to buy one CFL bulb and socket per week. No... I'd stick that money into a sock and keep adding to it each week until I could buy a light that had some intensity, come to think of it. I'm guessing that the eventual harvest would only be a week or three behind (and much more substantial ;) )....
 
I always feel I have to preface my advice with "I'm not an expert." I've got like 4 grows, 7-8 plants --- Anyway, 100-150 watts of CFL per plant would be good except the wattage (or light really ) needs to be spread out over the plant. In a 4X4 tent I'd say 4 plants would be full with minimum 400 watts CFL. I'm vegging one White Widow at 150 watts total--but arranged all around the plant.
 
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