Lighting and Vegetative Growth

Greetings and Salutations,

I'm a novice grower, and I have some questions concerning lighting during vegetative growth. I would be immensely appreciative of any help that you could provide to my queries.

My research has led me to believe that, after genetics, lighting is the most important requirement for vigorous plant and bud growth. Further research revealed that light emitted in the blue spectrum is more beneficial to plants in the vegetative growth phase.

Metal halide bulbs provide more light in the blue spectrum than high pressure sodium lamps thus helping to promote healthy stem and root growth with shorter internode spacing. So, what types of metal halide bulbs are the most efficient for vegetative growth? Why?

For example, the solarMAX 1000W Vegetative Metal Halide has a Kelvin rating of 7200 degrees and emits 85,000 initial lumens; its color temperature is the highest of all the horticultural lamps I have seen thus far which means it puts off a fair amount more blue light than even other metal halides.

The 1000W Sunmaster Cool Deluxe Metal Halide has a lower Kelvin rating of 6500 degrees and emits only 80,000 initial lumens; it provides a slightly more balanced spectrum than the solarMAX but has an incredible 320 PAR watts.

The 1100W Sunmaster Warm Deluxe Metal Halide by contrast has a Kelvin rating of 3000 degrees and a whopping 133,000 initial lumens; it provides light rich in the red-orange spectrum and a whopping 385 PAR watts.



Would the solarMAX be the best at encouraging the plants to grow short and squat, with little spaces between the internodes and greater lateral branching?
Are there any disadvantages to having the internodes spaced closer together?

Would the Sunmaster Warm Deluxe cause significantly greater stretching even though it has the greatest lumen output by far?
Could that stretching be averted by adding "Cool" CFLs to the grow room?
Would having more light in the red spectrum encourage more males?

Have you tried any of these lights? Do they have problems running on electrical ballasts?
Would the "Turbo Charge" feature on a Galaxy Select-A-Watt Digital Ballast offset the lower lumen output of the metal halides? Or would it be a recipe for disaster?

What other factors need to be looked at when selecting a bulb for vegetative growth?



Many thanks,
Polysmart

Veg - 5000-6500K
Flower - 2700-3000K
Not sure about your first example. I would like to know too.

Thank you Smallsn, but I don't think you answered my question. I wanted information about why a Kelvin rating of between 5000-6500 degrees is preferable for vegetative growth? Why not have a lamp with a higher Kelvin rating? Would the higher proportion of light in the blue spectrum provide any extra advantages? Or disadvantages?

For cultivators on a budget it's often recommended to simply forget about metal halides and get a high pressure sodium lamp. The reason being: high pressure sodium lamps put out more light over all. For example, the 1000W Sunmaster Super High Pressure Sodium Lamp gives off 150,000 lumens initially and emits 358 PAR watts.

Comparing the HPS to the "Cool" MH we can see that the HPS puts off almost twice the light of the MH. Yet with emitting it only half the light the MH provides 80% of the PAR watts of the HPS and that light would predominantly be in the blue spectrum. So what matters more: intensity? Or, spectrum?

grow it grow it grow it big my nig!

I would conduct an experiment...but conducting a good experiment requires significantly more time and money than I have at the moment...is there no one that would be able to answer my questions? Even partial answers, or answers to the other questions i.e. internode spacing, plant sex in response to light, lamp reviews, spectrum versus intensity, etc. would be much appreciated.

http://www.youtube.com/watch?v=16A6nYQJEyc

You could always buy a 1000w HPS and just use a MH bulb for veg and the HPS for flowering.

The reason why plants like blue in veg and red in flower is because it mimics nature. Blue = spring, Red = summer.
I have gotten good results from using HPS for veg. It produces nice stocky dense plants.
Although I have not used one before I have heard of good results from CMH lamps producing a broader light spectrum.

Thank you Rusty Crutch, I do intend to use a metal halide for vegetative growth and a high pressure sodium for flowering. Given that natural sunlight is rated around 6500 degrees Kelvin, do you know or have you heard any hearsay about whether the greater amount of blue light from the solarMAX would actually be utilized by the plants?

In response to that video, aren't there safety issues with putting a metal halide bulb in a high pressure sodium ballast and vice versa? Isn't it also dangerous to put a lower watt bulb in a higher watt ballast? Forgive me, I'm not very knowledgeable about electricity in college I was seduced away from the physical sciences by the social ones...less mathematics and more cute girls.

Polysmart said:

Thank you Rusty Crutch, I do intend to use a metal halide for vegetative growth and a high pressure sodium for flowering.
1. Given that natural sunlight is rated around 6500 degrees Kelvin, do you know or have you heard any hearsay about whether the greater amount of blue light from the solarMAX would actually be utilized by the plants?
2. In response to that video, aren't there safety issues with putting a metal halide bulb in a high pressure sodium ballast and vice versa?
3. Isn't it also dangerous to put a lower watt bulb in a higher watt ballast?
Forgive me, I'm not very knowledgeable about electricity in college I was seduced away from the physical sciences by the social ones...less mathematics and more cute girls.

Click to expand...

1. Just a guess here but you may experience more stretch with a higher temp rating. I've noticed that there is more stretch in plants vegetating under a MH than under a HPS and may be even greater with a higher color temp light.

2. I'm too scared to try it myself but I've looked around on various sites and a lot of people are putting MH bulbs in HPS ballasts of equal or greater wattage.

3. The wattage listed on the ballast is the maximum amount of power that is able to be drawn through the unit. eg. say for instance that a normal household light fixture can run 250w before something goes pop. It doesn't mean that you can't run a 14w CFL in it. The wattage on a ballast is just the maximum SWL of the ballast. It doesn't supply the listed wattage, It simply allows for the said flow of current.

Did that make sense?

Really..its funny that you guys are here discussing this because I came here with the same questions.....what is better for veg cycles. I see many people just useing cfl for their veg periods.....this cannot be better then a 400 watt lamp?

I only use CFL in the mother/clone box. IMO CFLs are a waste of money for Veg and flowering. I had them all over my last grow and they made little difference. With the money I spent on 7 X 24w spirals I could have easily bought another 400w MH/HPS light kit which would produce a hell of a lot more light.

not enough lumens to produce big fat buds with flo's, but great for clones. i completely agree with rusty

Again, thank you Rusty. Your explanation of how ballasts work made sense, but it inspires another question: why then is it dangerous to run a lower watt lamp with a higher watt ballast? If the lamp can only draw 400 watts would running the lamp on a 600 watt ballast have any effect on either the lamp or the ballast? Would it matter if the ballast was electric?

I'm only familiar with magnetic ballasts (not digital) but the ballast and bulb should be fine, just as long as the bulb is of equal or lesser wattage. If you put a 1000w bulb in a 400w ballast you would melt the ballast into a nice smoking puddle. There are a few videos on you tube that show people putting 400w MH bulbs into 1000w ballasts. They say that they've been doing it for years without a problem. Some people say that the bulb degenerates slightly faster which is the only downside I can find thus far.
I personally just run both veg and flowering with 1 X 400w MH and 1 X 400w HPS for an even mix. The buds that grew in the light overlap were massive (the size of my arm) compared to the buds under either the MH or HPS alone (coke cans). A lot of growers swear by a 1:2 HPS/MH ratio for veg and 2:1 HPS/MH for flowering. You will also need to get some reflective panels that you can move around the perimeter of the plants to reflect more light. You can greatly increase light intensity and penetration by laying a reflective panel against the "dark side" of the plants. It will be the difference between nice buds and popcorn in the low lit areas of your grow room. "panda" film or mylar is great for wall coatings but I use reflective "corflute" panels which you can just lean up against the plants.

Did someone say tight inter node spacing?? The Calvin Cycle, when plants are veg'n, is what will determine the overall spacing of your inter nodes and over all later branching. For this portion of plant growth you want to focus your light spectrum in or around 6500K. Producing waves the plants can't use only makes heat. Whether or not the 7200K is better I cannot say as I have not personally used one. I can and will however tell everyone that grows inside how to increase their yield over all as well as how to control your initial inter node length.

and NO, I'm not joking.

i used a 96watt coralife 6700k aqualight. and it works great for vegging. but as far as flowering goes, definately and hps.

Touchet said:

Did someone say tight inter node spacing?? The Calvin Cycle, when plants are veg'n, is what will determine the overall spacing of your inter nodes and over all later branching. For this portion of plant growth you want to focus your light spectrum in or around 6500K. Producing waves the plants can't use only makes heat. Whether or not the 7200K is better I cannot say as I have not personally used one. I can and will however tell everyone that grows inside how to increase their yield over all as well as how to control your initial inter node length.

and NO, I'm not joking.

Click to expand...

Think i'd have to agree as far a real world experience goes. Personally i'd say Ceramic MH for the win, but only available up to 400W. Use CMH w/some 6500K side/aux lights...good to go

the ufo and hps mixture is working wonders. the bud directly under the Ufo is by far the tallest

Going with (2) 85 watts 5,900lumens (<---LINK) in a 2x2x4 area. Is that fine ? just wondering what others think since its not the normal T5 setup

I like the questions you have posted! I myself was trying to figure out what to use this past week for veg. I started with a 1000W MH and oh lord the heat! Day 2 I swapped to T5's, but felt like I was shafting myself since a florescent is still a florescent. After a bit of reading I decided on a 400W CMH bulb for veg. I don't have a picture of inter-nodal spacing though, since I am on day 5.

As much as people say florescent light sucks, I cant see the harm in using it as side lighting for any grow. As a matter of fact I am just waiting on my brackets to come in so I can use my 8 bulb T5 as side lighting, then again, I think I will benefit from it much more in flowering after switching them from blue to red spectrum. Also will be going with 1000W hps for flowering, when that day comes!

Am I an idiot for going to the CMH 400W from 1000W MH? I am in a 2x4x7 space

Anyone questioning results on the SolarMax at 7200k take a look at the picture and you tell me. These things are growing like beasts with nice, short, compact veg growth. IMO more blue light is a very good thing. For Flowering, I'll go the opposite route, using a 2100k HPS (Ushio Opti-Red).