Do veg and flowering have different wattage requirements?

I'm looking to buy a few light bulbs. I was thinking 3 6k for veg and 3 2.7k for flowering, but what stage is more important for high yield? I don't want to grow too tall, but I want it to be dense. Would increasing wattage during flowering help at all?

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Hey plsfoldthx, welcome to RUI!

A rule of thumb for flowering is 50 watts HPS per square foot for a stationary light and 25 watts HPS per square foot for a light mover.

Veg takes much less, I use 90 watts for 16 square feet.

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Thanks for the welcome.

Just to get this straight. Do you think buying 4 2700 flowering bulbs and 2 veg bulbs would be better?

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"4 2700 flowering bulbs and 2 veg bulbs"

Is 2700 the color spectrum kelvin? What kind of bulbs, what wattage?

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Yea 2700K Spectrum. I was thinking two 40W 6500K and four 40W 2500K for flowering. Also, how many watts of CFL can I safely connect to one standard apartment wall outlet?

What about a two 125W bulbs? One for veg and one for flowering? It's gonna be built in a large box in a a closet.

plsfoldthx said:

Yea 2700K Spectrum. I was thinking two 40W 6500K and four 40W 2500K for flowering. Also, how many watts of CFL can I safely connect to one standard apartment wall outlet?

What about a two 125W bulbs? One for veg and one for flowering? It's gonna be built in a large box in a a closet.

Click to expand...

Sounds good plsfoldthx.

I think you should try to get at least one more 6500k bulb. If your worrying about size, you should try to focus more on creating a way to adjust the distance of the cfls to your plant. As you probably already know, the closer the light source, the less stretching creating a small and dense plant.

good luck!

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Pls this is a great chart for comparing light output for different bulb types.



CFLs and LEDs suffer from the Average Lumen Fallacy: "All that has to be done is to add bulbs until we have the same Photosynthetically Usable Radiation as an HPS" (PUR as opposed to PAR). The Average Lumen Falacy leaves us with a light intensity problem that requires much greater growing skill than does an HPS flowering lamp. You'll probably meet some of the best growers here on the CFL forum because they have to be better to get good yields from less resources.

Plant light receptors evolved to absorb intense light over a short periods through the day, then rest, then absorb again - they are less efficient at absorbing light from one stationary source over 12 hours; and a chemical signal is sent by the plant when it receives intense light: "Grow like crazy, hold nothing back! We'll get lots intense of light later because we got it before, hold nothing back!" Like exercising to loose weight - we don't just burn more calories while we are running, the body's metabolism speeds up and we burn more energy 24/7, even when we are sleeping.

If you're a Stargate Atlantis fan think Wraith biologically based Hyperdrive vs Ancient technologically based. The Wraith's drive has to rest at short intervals but will heal itself like any living creature. Trade offs. Plant Light Receptor vs Solar Panel.

https://www.rollitup.org/advanced-marijuana-cultivation/314052-plant-light-receptors.html

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ALF can be overcome with an Elliptical Trough Reflector but for the time being just add up your lumens for an approximation. There are posts in this sub forum that will give you the exact number of each bulb that experienced CFL growers have used with success - use the advanced search function at the top right of this page, try "cfl bulbs" for the tag and "cfl growing" to limit search to this sub forum. It always helps me to see pictures of other people's grows.

https://www.rollitup.org/grow-room-design-setup/309037-solving-fatal-flaw-leds-experiment.html

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The closets to PUR that we are going to get is Lumens:

Lumen is the visible light spectrum for humans: A typical human eye will respond to wavelengths from about 390 to 750 nm.

Photosynthetically Usable Radiation (PUR) is the light spectrum that plants absorb FOR ENERGY. The plant absorbs radiation outside PUR as signals - for example, far red / orange causes what's known as the Emerson Effect - it sends or keeps a plant in flower, even if the dark period is interupted with a 30 minute period of PUR light.



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The PUR (Photosynthetically Usable Radiation) spectrum are the peaks of chlorophyll a & b's absorbtion, the two ends of the Photosynthetically Available Radiation (PAR) spectrum.



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Thanks for the useful info guys!! End of light, I didn't know that about the distance of the light and the height of the planet. What about two 125w CFL for veg and 125w for flowering. I know the 125watts use a mogul base. Would having two 125w CFLs as well as a fan running overload standard apartment wall outlet over a large period of time or would it give off a suspicious power signature you think?

Hobbes, great resource! Just one question. That first chart, is that equivalence in PURs or just Lumens? Because I noticed one 125w CFL is roughly equal to EIGHT 40w CFL?

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"What about two 125w CFL for veg and 125w for flowering. I know the 125watts use a mogul base."

Extra bulbs will help - they will allow you to cover more area, but will not give you more depth penetration or much better intensity. You still need very short plants, some type of stem training.



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"Would having two 125w CFLs as well as a fan running overload standard apartment wall outlet over a large period of time or would it give off a suspicious power signature you think?"

250 watts is nothing for power use, my TV is rated for 125 watts. If you're concerned about power use for whatever reason consider a small HPS, one 150 watt HPS spot light from Home Depot will put out 3 times the lumens and better intensity than 2 x 125 watt CFLs. As well, the bulbs are more efficient and will give off less heat, the ballast is remote and can be kept out of the grow area for further heat reduction. The HPS bulb gets hotter than the CFL, in a small area, but there is more heat given off by CFLs for the same wattage. Watts In = (Light + Heat) out

250 watts CFL x 12 hours per day x 365 days per year = 1,095 kilo watt hours per year.

Just between the usage of a washing machine and a fridge. If you got a less expensive 150 watt HPS spot light from Home Depot:

150 watts HPS x 12 hours per day x 365 days per year = 657 kilo watt hours per year.

If you bumped up to a 250 watt HPS and ran it for 8 hours a night - when rates are cheaper and no one is checking the power meters for usage:

250 watts HPS x 8 hours x 365 days per year = 730 watts <<< this would be my choice: less heat; less power; better yield; better potency.



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IMHO it is better to use twice the wattage for half the time period, with a light mover. The extra intensity will push the plant's light receptors to send chemical signals to the buds to spare no horses when growing. Deeper penetration into the canopy, better developed buds lower on the plant.

To cut down on heat in my attic grow room this summer I experimented with 6 light / 18 dark, something I picked up from Subcool's forum. Yield is reduced, flower time extended, but potency stays the same and yield is perhaps 75% with 50% of the power use.

Another variation is 6 light / 12 dark - an 18 hour day. This gives the plants their regular 12 hours darkness and gives us 4 x 18 hour days every 3 x 24 hour days. Reduced yield but reduced flowering time as well. This style of growing requires a 7 day timer and the light period that you can work in the garden changes, you'll need a Green Eye lamp.



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"That first chart, is that equivalence in PURs or just Lumens? Because I noticed one 125w CFL is roughly equal to EIGHT 40w CFL?"

It's in lumens but for practical purposes at this stage of your decision making consider PUR and lumen to be the same.



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