I would appreciate some advice.
I have lumens per square foot of growing space worked out. So I end up with 4, 105 watt cfls. I understand about the kelvins and all that but I am unsure of how too mix them up. I can have 2 6500k bulbs for vegging and 2 2700k bulbs for flowering. Should I run the flowering bulbs all the way through or can I use vegging bulbs in their place untill flowering occurs? and then should I take all the vegging bulbs out and put in all flowering bulbs? Simply put... do the color spectrums have to be balanced throughout the grow for optimal growth?

Good question Janko. You're bound to get a variety of answers, but for myself, I use only 6500Ks when vegging, and only 2700ks when flipped. Some growers mix in a few bulbs of the 'other' spectrum for balance (or some other vague notion..). Your best bet would be to try both and see which works best for you.

Good luck

I, too, use blue light(6500) for vegging and switch to red(2700) for flowering. So far (3 grows) that has worked out well for me. I have been gonna put a little blue, like a reptile bulb or something, in when flowering as i have read that it increases the thc content, but have yet to get it done.

Thanks for the replies. I'm trying to establish a basic method for my first ever grow. I can change things up after I gain some experience I suppose. For this grow I will go with 3 6500k for vegging and 1 2700k then I'll switch for flowering. 3 2700k's and one 6500k. I'm a chronic worry wart. It's tough for me to make a decision some days.

Hey Larry, would you have a link or reference for that ? Not being a jerk, just like to discern between fact and myth, particularly when it comes to our favourite herb.

Has anyone compared mixing spectra vs. consistency ?

When i say "blue light" i'm considering a 10,000K reptile light.(low watt)I have an MH 10,000k(400w) i have considered using for short periods of the flowering cycle, but haven't gone to the work of setting it up on a seperate timer.And i'm afraid it's a little strong. My results have been fine w/o so far. "If it ain't busted, don't fix it".

So I have Ed Rosenthal's Marijuana Grower's Handbook and there a part in here that states this:

" The amount of UVB light a plant recieves affects THC and terpene prduction. Plants grown under higher UV levels are more potent.
The amount of UV light that an area recieves is determined by latitude, season, climate, and weather. Light reaches the equator most directly, and is the most intense. As the latitude increases light reaches Earth at a more oblique angle so it becomes less intense.
Throughout the northern hemisphere, which includes North America and Europe, UV light is at its lowest levels in December and January. After these months, the levels start rising. The further from the equator, the longer it takes to peak, the shorter the peak period and weaker the light.
For instance, in San Francisco ( latitude 37.75 ), UVB reaches its peak with a UVB index between 9-11 around May 15th. It stays there until around August 15th. By Sept. 1 it drops to 8 and by Oct. down to 6.
If you can ripen plants during the peak UV period the plants will be most potent. As the season wears on and the UVB levels decline the marijuana does not attain the same potentcy.
Using this information, no matter where you live, even in the far north you can grow potent
plants using light deprivation, so that plants ripen at the peak period rather than late in the season.

I have read that also but it was a piece on "altitude".



My uneducated guess. It sure sounds good doesn't it? One day I will get to that point and I will try it also.

Larry, what does blue light or MH have to do with UVB ? Am I just not reading your post correctly ? It could just be me on meds at the moment....

UVB is on the blue side of the spectrum. MH is higher in the blue than HPS, which is on the red side.

Larry, that is all well and fine, (as well as obvious), however although MH is more blue than HPS, MH still do not emit UVB, afaik.