4k MH for flowering?

icarius91

Member
hey guys, gona be getting an 250w Mh system soon and was wondering if i could use MH for flowering, and if i used a 4k MH instead of the 6500k MH would the plant flower better or would it not make a difference?

im a bit new to indoor growing so sorry if it sounds like a stupid question. im also growing on a bit of a budget and can only afford an MH system and not both or a conversion kit so im hoping to do MH thru the whole grow. thanks in advance.
 

eatsleepjdm

Active Member
no, the light spectrum is wrong, the flower cycle needs orange reddish spectrum and the MH is blue white for veg. you could use it yes, but the results will be far less satisfying
 

OregonMeds

Well-Known Member
It's better to veg and flower with just a hps rather than just a halide given a choice but it will work. Hey people grow with cfl's and halide is still way better than cfl's for flowering even though it is the wrong spectrum it's still the second best light you could have and you could do a lot worse.

If you have the choice just get hps, but if the halide is all you can afford don't hesitate to use it, it's sure better than nothing. I'd estimate 20-30% less yield than the same size hps which is still better than the yield you'd get off the same power in cfl's.

Here's a plant in the pic attached that I grew with only a 250 halide, and yes it yielded great smoke.
 

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icarius91

Member
wow actually that looks pretty nice to me lol. thanks alot for the info! +rep... i was originally going to do a cfl grow with the same wattage but then i noticed for the total cost of building a grow box my self and getting all the lights and equip i could get an MH instead.
 

OregonMeds

Well-Known Member
You'll still need a box or some way to control the light cycle to flower though...

I still use my 250 halides to veg even though I have plenty of larger lights now but I only use cfl's to save electricity in the rest of the house. You'll always have some use for the halide.
 

eatsleepjdm

Active Member
not to call u out but u said just halide and theres obv red spect cfl which would make a good diff


It's better to veg and flower with just a hps rather than just a halide given a choice but it will work. Hey people grow with cfl's and halide is still way better than cfl's for flowering even though it is the wrong spectrum it's still the second best light you could have and you could do a lot worse.

If you have the choice just get hps, but if the halide is all you can afford don't hesitate to use it, it's sure better than nothing. I'd estimate 20-30% less yield than the same size hps which is still better than the yield you'd get off the same power in cfl's.

Here's a plant in the pic attached that I grew with only a 250 halide, and yes it yielded great smoke.
 

OregonMeds

Well-Known Member
I am pretty certain that plant never had a cfl on it and I don't recall lighting anything from underneath either but I could be wrong, it's been a while.

Maybe I just moved that out of the way for the pic or something, I was using cfl's for the clones and to light the closet in general because I yanked the overhead light out to put in a vent.

I still use the same cfl for general lighting in there with the same 250 halides so it probably was just laid there to get it out of the way for the pic.
 

icarius91

Member
yea im currently working on making a 3ft deep, 5 ft wide, 6 ft tall box to help keep light inside from being wasted and light from outside wont penetrate it. i i was thinking of maybe running 2-4 26w cfl 2700k along with the MH during flowering for them, think that would make abit of a difference?
 

OregonMeds

Well-Known Member
If the largest light you can handle heat wise is a 250 get that, use that, but if you think you can handle more skip adding cfl's and just get the next larger light up like a 400.

I would not use one 250 in a box that large it's nowhere near enough, you need a 400 if you intend to use much of that space or two 250's just for the width alone not counting so much height...
 

icarius91

Member
heh well good thing im using shelving braces for the support structure....ive got more 3ft bars if i need to drop the width, im sure my calcs are off i just used the 5ft bars cuz i was looking at how wide my outdoor plants got.... think i could fit 2 plants in a 3x3 space without making it too cramped then? and for height its only 6 ft so ive got room to work with, cuz i can always put stuff under the pots to make them higher.

also just noticed the 2nd part of my main question wasnt fully answered lol, will a 4k MH give out a tad bit more red thus making it better then a 6500k MH for flowering or is there just way too much wasted energy to even be worth it? the light is coming with the lamp (bought it last night actually, 100$ shipping included) and the seller labeled it as a "grow" light but i thought 4k wastes too much on yellow and green which confuses me...
 

OregonMeds

Well-Known Member
4k would PROBABLY be better than 65000k for flowering but you'd have to compare charts of their performance to see the full spectrum graph to be sure. When a bulb is marked 6500k it means peak light output is at 6500k but it's also putting out more than just 6500k it's also putting out light at other spectrums at various levels.

Only after comparing spectrum graphs will you know for sure, after you compare how much light is put out at both 6500k and 2700k.

Here are some examples of the spectrum charts:
http://www.sincal.net/english/uvcurves.htm
 

icarius91

Member
well thanks for all the info! i think now ive got my setup tweeked enough that it wont have wasted space, and i think ill try that 4k bulb and maybe at some point flower with just the 6500k and see how much of a difference it really makes.:peace:
 
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