Question about 6500K watts during flowering

Anybody ever used 6500k lights for entire grow- I know it’s not recommended but I’m just wondering if anyone’s every tried it or heard about it… If so, does it make flowering longer than normal or does it decrease yield emencely or just a little?

I have 4 CFLS on one NL plants. One is 6400K-125watts (actual watts), two are 6500K-105watts (actual watts) and the smallest is 2700K but only 28Watts (actual) on the bottom of the plant. It is showing signs of budding but it don’t look like 5 weeks into flowering, does it? lol

Will it take longer with these lights or will the buds be significantly smaller? Because I can handle it taking too long lol but I’d rather take to long to ripen than it take the average time and not be as dense…

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First she’s sativa dom so will take longer to finish that is a given. Second mh 5500-6500k doesn’t have the same lumens or light penetration as HPS 2500-3000k so your plant will flower slower and with airy buds by comparison red light warm white CFL. Your plant will thank you for a change of light spectrum and your buds will be worth the change.

I know I referred to mh and hps but I am actually comparing light spectrum so same rules apply spend the money it will pay for itself :slight_smile:

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Okay, I see. So can I mix the light spectrums in any way?

Thanks for the fast response!!

I thought NorthernLights was Indica dominate?

you can mix light spectrum but you do want it fairly balanced or more so on the red scale if anything leaving 1 or 2 6500k won’t hurt by any means but the red helps more and is what you want. Northern lights is a hybrid as such can present genes of any of it’s ancestry the beauty of growing from seed look at your leave structure long and thin like fingers. Indica’s usually present with broad wide leaves this isn’t a bad thing just a way it’s genes are and can be different from seed to seed.

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I think you’d prefer it is only presenting in the leaves as a sativa could be 6ft tall and large node spacing it looks healthy and like a very nice cross imo

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With fluorescent lights, especially ones that are specifically made for growing plants, I don’t have any problem using 6500K the entire grow, after all the color of sunlight is 5800K on a clear day, and 6500K on a slightly cloudy or overcast day, and this is true even in the fall/winter when cannabis flowers outdoors naturally.

It is true plants can use more red, especially during flower, and this is why people use a light more in the 2700Kish color during flower. And there is evidence that more red light during flower may also help the plant finish earlier.

The main reason with HID growing that many people use the 2500K during flower is because HPS has this color normally, not so much because this color is actually necessary for flower. It is just that too much red during veg can cause the plants to stretch too much for very lanky tall plants with long spaces between internodes. And so it is more important the other way around, not too much red light during veg, and not that the plant specifically needs more red or less blue during flower. And MH tends to have a naturally blue-er light also, and is more often used for veg as it doesn’t have as much lumens or PAR per watt as HPS.

If buying the extra bulbs isn’t in your budget right now, use what you have. Then later you can try the redder lights and share your experienced differences in bud quality and yield results, I’m sure many people thinking of using fluorescent lights their whole grow will like to know your experience.

happy growing,



Okay I see thank you for such great information!!

Thank you.
Such a relief lol buying more lights is a little pricey . Especially right now … I will definitely let you guys know how it goes!!

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