MH vs HPS Veg/Flowering

I'm currently reading Ed Rosenthal's "Grower's Handbook" chapter on lights. In it, he claims that the practice of vegging with MH lights, and flowering with HPS lights "isn't used anymore because it's "generally recognized that plants grow as well vegetatively under HPS lamps as under MH", and that MH lights "are not used that much because they emit less total light than HPS lamps and produce lower yields." However, when I search on Google and this forum, I tend to see that almost everyone is recommending to use both MH and HPS lights for vegging and flowering, respectively, so which is it???

I run a mix of the two, and love the results.

nick88 said:

I run a mix of the two, and love the results.

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Okay, but if you haven't experimented running with just HPS only, how do you know whether your results would be the exact same, better, or worse? This is what I'm interesting in knowing before I start to purchase equipment.

In The rev tlo book his says he only uses 400 eye blue hortilux i would like to see The results. Does anyone actually just use mh

I have grown with just MH, with just HPS and with the combinations. If using just one light make it HPS.

amarti848 said:

In The rev tlo book his says he only uses 400 eye blue hortilux i would like to see The results. Does anyone actually just use mh

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I have grown with straight MH and you get pot. You get more pot and better pot with HPS added to MH or with HPS alone.

hotrodharley said:

I have grown with just MH, with just HPS and with the combinations. If using just one light make it HPS.

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If you grew with all combinations of lighting, did you see any difference in results?

doniboy said:

If you grew with all combinations of lighting, did you see any difference in results?

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Oh yes. The plants vegged under the MH took off like a rocket under the HPS much quicker than any raised under CFL. But that boils down to a day or two of acclimation to HID.

Personally I would recommend to inexperienced growers to use HPS and add some blue lights during veg by using some 6500K CFL around the plant to supplement the blue end. Overall the increased heat and less light penetration from MH make them not that desirable.

hotrodharley said:

Oh yes. The plants vegged under the MH took off like a rocket under the HPS much quicker than any raised under CFL. But that boils down to a day or two of acclimation to HID.

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So in you're experience, would you say using HPS for both vs using a combination of MH and HPS produced somewhat indistinguishable results?

hotrodharley said:

Personally I would recommend to inexperienced growers to use HPS and add some blue lights during veg by using some 6500K CFL around the plant to supplement the blue end. Overall the increased heat and less light penetration from MH make them not that desirable.

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Ahh okay that sounds like a good plan. Thanks.

HPS in veg leads to major growth and very long spaces between nodes.
If it isnt a strain that swells really big you end up with a lot more smaller buds than big fat cola buds.

MH keeps the nodes tight in veg and during the stretch and you end up with buds bumping into other buds forming one big giant bud.

I used enhanced spectrums in both veg and flower. Enhanced spectrum MH in veg is switched to enhanced spectrum HPS in flower.


It is also very important to keep in mind a lot of the books people read on cannibas and growing are pretty old themselves.
The amount of advancement in MJ in the past 10 years is more than it has been in the past few hundred years and we are getting more info and data regularly. The thing about science is, it always changes when you find new information. Enhanced spectrum bulbs make a lot of difference then the pure MH they used 10+ years ago and the pure HPS they used 10+ years ago.

The metal halide and hps bulbs I see at the hardware store are junk compared to the bulbs I am using.

doniboy said:

So in you're experience, would you say using HPS for both vs using a combination of MH and HPS produced somewhat indistinguishable results?

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So indistinguishable that the only reason I even still use MH is the cost of the low bay shop fixtures I bought. 400 watt MH with the bulb - used - for $20. I use them to veg. They were advertised as "grow lights" and "high pressure sodium" but they were MH. They beat CFL.

Again, if just one light or to make your grow simple I would recommend just HPS alone.

I'm getting conflicting info lol. Some people say it there's little to no diffidence with using 100% HPS and others say you'll get a better outcome (bigger more compact bud) with a combination of the two...

althor said:

HPS in veg leads to major growth and very long spaces between nodes.
If it isnt a strain that swells really big you end up with a lot more smaller buds than big fat cola buds.

MH keeps the nodes tight in veg and during the stretch and you end up with buds bumping into other buds forming one big giant bud.

I used enhanced spectrums in both veg and flower. Enhanced spectrum MH in veg is switched to enhanced spectrum HPS in flower.


It is also very important to keep in mind a lot of the books people read on cannibas and growing are pretty old themselves.
The amount of advancement in MJ in the past 10 years is more than it has been in the past few hundred years and we are getting more info and data regularly. The thing about science is, it always changes when you find new information. Enhanced spectrum bulbs make a lot of difference then the pure MH they used 10+ years ago and the pure HPS they used 10+ years ago.

The metal halide and hps bulbs I see at the hardware store are junk compared to the bulbs I am using.

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Can you link me to or give me the name of the "enhanced spectrum" equipment you use so I can research it? You basically use MH lights with enhanced spectrum lights for veg and HPS with enhanced spectrum lights for flowering?

harley, if i were to buy a cfl fixture, would you get a 6400k or 2700k for veg and flower?

i was thinking i would get the 6400k for veg and flower becuase the 6400k is closer to the uv light and not the infrared light.

i could always buy both, but if i had to choose one and couldnt use supplememental lighting from the opposite spectrum?

right now i run a mixed spectrum, but i want to buy a 4 bulb t5 and they will only let me choose 4 6500k OR 4 2700k bulbs.

pretty old - i resemble that statment - 63 here

but i have used a 250w hps-eye hortilux and a 250w cmh - phillips for a long time now i had to get rid of one it had a built in ballast and brought the heat


this was my madness before



this now
[video=youtube;UCrdRO-_-hA]http://www.youtube.com/watch?feature=player_embedded&v=UCrdRO-_-hA[/video]


but mh or cmh better for veg

mh or cmh better for the first 1/3 of flower - it will reduce your stretch
2nd 1/3 of flower better served by hps - it will give you rock hard buds if in the genetics ( cant get rock hardd from a flufy bud producer)
last 1/3 of flower better served by mh or cmh - it will brimg the best results from the finishing stage that bulk up time

the ugly slopy fire waiting to happen pic -the light on far side was opened to see if i could use the ballast found the ballast to be switch hitter was either 250 or 400w so i put in a 400w bulb for hps an keep my 250w cmh -one day to swap out for another 400 in the growzilla double bulb

yep im old i hope you make it

I an I

Rastarfari

[video=youtube;2HqgL1CPwT4]http://www.youtube.com/watch?v=2HqgL1CPwT4&feature=player_embedded[/video]

just got dis

might use 6400k for first 3 weeks of flower because of you

bmeat said:

harley, if i were to buy a cfl fixture, would you get a 6400k or 2700k for veg and flower?

i was thinking i would get the 6400k for veg and flower becuase the 6400k is closer to the uv light and not the infrared light.

i could always buy both, but if i had to choose one and couldnt use supplememental lighting from the opposite spectrum?

right now i run a mixed spectrum, but i want to buy a 4 bulb t5 and they will only let me choose 4 6500k OR 4 2700k bulbs.

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6500K for veg and they can be hard to find. When you do find them they are invariably low wattage. Make up for that by using more. Then the big 55-watt/200-watt comp output CFL bulbs in 2700K really rock for side lighting spots on flowering plants. Those are very easy to find.

doniboy said:

I'm getting conflicting info lol. Some people say it there's little to no diffidence with using 100% HPS and others say you'll get a better outcome (bigger more compact bud) with a combination of the two...



Can you link me to or give me the name of the "enhanced spectrum" equipment you use so I can research it? You basically use MH lights with enhanced spectrum lights for veg and HPS with enhanced spectrum lights for flowering?

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OK in short, the more you can present the plant the light it needs at a given point in its life with the spectrum it needs right then the better off the plant is. It's the blue end for early growth (6500K CFL or MH) with the red end coming more into play for flowering (HPS or 2700K CFL).

My statement began if choosing just ONE light to grow under then make it HPS and I will stick to that and defend it for MOST growers. The newer ceramic HID lights are fantastic - and expensive as all hell.

My answers usually hinge based on what the OP claims as experience or what I perceive. When a oster asks a simple question about lighting that experienced growers already know the asnwer to then it is best to KISS.