I have searched upon this topic.

I see conflicting results.

Some things that are the same are that,

MH: UVB helps produce slightly higher concentrations of THC and resin

HPS: Buds are more stretchy, but better in some ways
.

But, I have yet to find any threads with documented grows, maybe clones, showing the comparison between MH and HPS Flowering cycles.

Anyone with photos?

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Sorry mate, no pics, but I will say this:
The best lights for vegging and flowering are horticultural HPS bulbs.
The UVB light produced by MH is very low. I always buy a special 10% UVB light from pet stores in order to get that really sugary trichome production.

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HPS is the best for flowering
MH is best for vegging
Its because of their spectrums
if you add the 2 then its even better, not saying mh wont grow good bud its just not as ideal as hps. MH is best for veg

i do fluoros for starting
mh to veg
hps for flower.
but even tho ive never used them, from what i hear i would have to agree with doc cannabis. i will try those hort. bulbs someday.

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I use both... I use the Solarmax1 bulb which is a 400mh & a 600hps in the same bulb..... expensive, but the results are uncomparable... you need a 1000watt hps ballast to run it.
Using both spectrums, gives some unreal buds

I've done both, this grow I switched back to HPS because I feel that the MH takes too long to finish. I like the MH, it helps keep the plants compact and has a better coloUr rendering index for working in the garden. The buds were less fluffy, more solid but smaller than HPS buds. A little less weight/volume at harvest.

I haven't measured it but I think the plants take a bit longer to switch from veg to flower with MH, the HPS 2100K coloUr tells the plant that summer is over. A 3000K to 4000K MH may have summer coloUr, one less thing to entice the plant to switch to flower. Be sure to use a full spectrum bulb like the Sunmaster Warm Deluxe. I've got a Hortilux Daytime MH, around 5000K, it's suppose to be one of the closest bulbs to real summer time daylight. I've had it for 2 years and have yet to work it into the garden, should be interesting buds.

I found everything else pretty much the same.

I've chatted with several growers who use MH, even a commercial grower who uses HPS for business and MH for personal stash. They say there is no difference in potency.

As for UVb I just started using the same Lizard Lights as Doc Cannabis today.

.

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why is this crap in advanced growing ?

Quiet noob.

Because this has not been fully Documented yet, I have not seen anyone posting results where a MH versus HPS were grown side-by-side.

Until then, I think both have unconfirmed truth's and lies.

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I lift weights n stuff bro'

OMG, I cannot believe what I'm reading here..
Look, MH's are great for VEGitive growth because of the Blue~White Spectrum, which Promotes Growth...
HPS which is on the more yellow/red/Orange ends of the Light Spectrum are more condusive for Flowering....
There is 'NO" unconfirmed BS, whether MH vs. HPS is better for flowering vice versa..
I've seen Many examples side by side, and by My own experience..
HPS is better.. Think, your in effect fooling the plant, manipulating photo-period in the Light HOURS, plus using the red/yellow ends of the Light spectrum, the plant "senses" that "Fall" is approaching, thus produces flowers,, ie: buds...
think about it...

Would this work on a digital/electronic ballast? It runs both HPS and MH.. I wonder.

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