HPS for veg????!!!

OK everybody. I know there varied theories on this and would love to get as much feedback as possible.

I am setting up my grow room and am doing research like a mad man!

I want to be as prepared as humanly possible. I understand the only true way to learn is to do but competent and thorough legwork can prevent allot of amateur mistakes.

That being said, I am curious to the benefits of different lighting for different stages of growth. I have a small understanding of of the different light spectrum emitted from different sources. I am just curious to the effects of each. I have read post after post and was just looking for some direct answers. I guess the best way to do this is to just number a few questions and anyone can answer the ones they see fit. Thanks in advance.

1) Is it bad to veg under HPS?
2) It seems veg wattage is always lower than flower. If using one type of light source should I reduce my wattage for veg (2000w HPS planned)? In the same thought, I have a switchable ballast, is using the same wattage for MH/veg and HPS/flower bad?
3) What is the effect on yield?
4) obviously less wattage means less $$$, but is that one of the major factors (aside from the spectrum reasons)?
5) What are some of the benefits to using multiple light sources (with reproducing as much of the sun's spectrum a given)?
6) what are some of the ill effects of using a single light source?

I know it's a long post with allot of questions. Any help would be greatly appreciated.

I would like to know a few of the same things

1. You can veg under HPS without any problems at all. Period.

2. How would it be bad using same wattage for veg and flower?? If anything its Better. Veg wattage is usually lower then flower to save money. You dont need the extra wattage to penetrate a thick flowering canopy. You can get fast vigorous veg growth with less wattage so why not. Higher wattage for veg just means bigger, faster growth, and your plants will be ready to pack on the buds.

3. Everything....

4. ????? same as question 2?

5. Multiple light sources means more coverage. More lights means you can grow more weed.

6. I wouldnt say theres any direct ill effects from 1 light source, it depends how many plants your putting under this single light source and the style of grow.


Your over thinking this just a little....keep it simple.

And all of these questions could have been answered if you search the forums or you could just google it.

I just think the redder spectrum would cause stretch?

lower the light. Ill be using a 150w HPS till chop. If you have good ventilation and air movement, you can get the HPS's pretty low.

They wont stretch, but HPS is definitely better for mothers that are being harvested for clones, HPS produce lots of shoots during veg.

as far as i know you can use an hps for both vegging and flowering without any trouble, but hps i think is definitely the best choice for flowering period. for vegging they use more of a blue spectrum so you might want to consider the metal halide. another thing to consider though is the lumen output vs. wattage for hps vs. metal halide, although metal halide puts out more light in the spectrum they can use they also put out less lumens and are less efficent then hps.

BCtrippin said:

1. You can veg under HPS without any problems at all. Period.

2. How would it be bad using same wattage for veg and flower?? If anything its Better. Veg wattage is usually lower then flower to save money. You dont need the extra wattage to penetrate a thick flowering canopy. You can get fast vigorous veg growth with less wattage so why not. Higher wattage for veg just means bigger, faster growth, and your plants will be ready to pack on the buds.

3. Everything....

4. ????? same as question 2?

5. Multiple light sources means more coverage. More lights means you can grow more weed.

6. I wouldnt say theres any direct ill effects from 1 light source, it depends how many plants your putting under this single light source and the style of grow.


Your over thinking this just a little....keep it simple.

And all of these questions could have been answered if you search the forums or you could just google it.

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First, thank you very much for a speedy and informative response. I was trying to keep it simple hence the single light source but I also want the best results as possible. I have had 4 successful outdoor harvests and am moving indoors for the first time. Therefore, I am concerned about the learning curve for lighting and nutrients. Belive me I have been on the forum for about 8 hours. That is more so what spawned the question, but no worries you aced it and put it to rest so thank you very much. M/H here I come!!!!

Thanks to all who replied

Just get a mh/hps ballasts. You flip a switch on the ballast and you can use it for HPS or MH. It just disables the ignitor for the MH because it doesnt need it. I have one and they are great because you dont need expensive conversion bulbs or another ballast.

BCtrippin said:

Just get a mh/hps ballasts. You flip a switch on the ballast and you can use it for HPS or MH. It just disables the ignitor for the MH because it doesnt need it. I have one and they are great because you dont need expensive conversion bulbs or another ballast.

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I already did !!! I went with two of the Extrasun 1000w switchable ballasts. Looks like I made a decent choice. I wanted flexibility and the option to change without having to purchase anything other than bulbs. To be a little bit of an asshole now that I have you here (being lazy, I know there are threads out there for just this) any thoughts on 18/6 vs 24/0? Thanks again for your input.

Isaid'Ello said:

I already did !!! I went with two of the Extrasun 1000w switchable ballasts. Looks like I made a decent choice. I wanted flexibility and the option to change without having to purchase anything other than bulbs. To be a little bit of an asshole now that I have you here (being lazy, I know there are threads out there for just this) any thoughts on 18/6 vs 24/0? Thanks again for your input.

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Definitely 18/6. Plants need time to sleep. Some people prefer 24/0 for seedlings or clones, but I think the difference is minimal. Definitely 18/6.....and you save on power.

BCtrippin said:

Definitely 18/6. Plants need time to sleep. Some people prefer 24/0 for seedlings or clones, but I think the difference is minimal. Definitely 18/6.....and you save on power.

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BC you rock!!! Thank you so much for your advice. Keep an eye out for my grow journal (probably 2 weeks or so) so you can see how you advice has helped. just waiting on seeds to get to the safehouse. Bulbs too, now!

I'm in my first grow, so take it with a grain of salt. I have a 400W HPS/MH switchable that I got for $200 new -- I love it for my goals. I have 8 plants underneath it and they all get plenty of light. I'm having some nutrient issues, but the light power and growth has been great. The ones without nute issues are growing gonzo -- it's inspiring.

HPS can be used all the way from seed to harvest. I've seen some say that indoor maturity takes an extra week under HPS, but HPS runs cheaper than MH. I've seen a rule of thumb stating that for every 500W of continuous output, you can figure about an extra $20 a month on your electric bill (of course, power rates vary tremendously across states and countries). There is also the SonAgro 430W bulb, which you can run in a 400W HPS ballast. This bulb has some enhanced spectra and a few extra watts without needing a more powerful ballast -- I haven't used one, but have seen good reports.

A couple of things: 1) Each individual light covers a small amount of space - check your manufacturer specs on this. One 400W is good for about 12-16 square feet. Allocate about 1 square foot per plant, decide how many plants you want, and that will give you an idea how much light you need. There are some calculators on the 'net for this. 2) My light, and others I suspect, do not put out their light evenly. Get a light meter and search around under your light for the "peak" spots and center your plant tops underneath them (I did this, and my growth just exploded right after). Or, get one of those rotating devices to assure even light spread. The "weak spots" under a light are the same as outdoor shade, so whatever you do, make sure your plants aren't struggling away underneath one of these.

Im with ya there BC, but if u do go single source, get the maximum lumens u can, check out GRO-LUX brand bulbs.Decent price and max lumens.

Thank you Kriegs for another in depth and informative post. I am going with (2) 1000W lights for 12 plants in a ebb & flow bucket flood system. I already have the switchable ballasts so using two light sources means I only have to buy M/H bulbs. I definitely need to invest in a light meter but my set up has already set me back...... enough lets say. I'm hoping with 2000W I should get enough coverage to not be an issue. So thank you very much for the advice and you too Beeker. I hope this thread is also useful for other too!!!

Holy crapinola... w. 2000W, you'll be doing some serious producin' sweet! Probably not going to have many "weak spots" under that setup.

Kriegs said:

Holy crapinola... w. 2000W, you'll be doing some serious producin' sweet! Probably not going to have many "weak spots" under that setup.

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No shit....great lights. Hows the heat?

diemdepyro said:

No shit....great lights. Hows the heat?

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I run 2 1k HPS, and a 7000 BTU AC to handle the heat.

Hahaha! yeah, 2k is allot for only twelve buckets, but the system i bought can handle up to 48 (according to the manufacturer) buckets. I am going to max out at 24. But I wanted to get the room dialed in with a smaller harvest first. I'm in a basement in a climate that is cold to cool for another 3 months. I also have a pretty good space, 10x11x8. Just hung lights two nights ago. I'm running an average of 85 degrees with little to no ventilation set up (yet). Thanks for the interest and advice guys. Just placed my seed order last night so watch for my journal.