The Basics Of Plant Lighting

[Hosebomber]

Get a 250 watt MH bulb. The pulse start current could likely be enough to make it pop should it attempt to restart after a power outage/ lose connection. If you are starting it cold it will work (at least for a little while), it will simply lower the life of the bulb. However, it is not worth the risk of a bulb shattering.

 

[comedian]

I'll admit that I didn't read ALL the replies, so this might have been asked already! But here goes:

From the research I've done already, it seems that 7,000-10,000lm per square foot is the recommended lumen output, so my question is: if I have a space of 24 square foot and I need at least 7,000lm, does that mean I'll need at total of 168,000lm for that area!?

That seems like a lot of bulbs!? How many CFL bulbs is that, or what's the best way to achieve those high numbers with CFL bulbs!?

Thanks in advance!

 

[Graytail]

CFLs produce roughly 70 lumens/watt, so ... 168,000 lumens = ~ 2500 watts of CFL.

Dat's a LOT of CFLs!

You're far better off with HID lighting at that wattage. I ran a 600+ watt CFL rig when I started and wish I'd skipped that and gone straight to hps - CFLs aren't a good investment at that power level. You get 70,000+ lumens from a 600W hps, for instance.

 

[comedian]

CFLs produce roughly 70 lumens/watt, so ... 168,000 lumens = ~ 2500 watts of CFL.

Dat's a LOT of CFLs!

You're far better off with HID lighting at that wattage. I ran a 600+ watt CFL rig when I started and wish I'd skipped that and gone straight to hps - CFLs aren't a good investment at that power level. You get 70,000+ lumens from a 600W hps, for instance.

Yeah! That's what I'm screaming, brutha! I'd need a thousand light bulbs for that! That's why I ask because they seemed a bit crazy to me!

Btw, that's right, though, right!? I mean the amount of lumens needed for that 24 square ft area!? 168,000!? I guess I'll start reading into HID bulbs!

Thanks for the quick reply!~

 

[Graytail]

Yeah! That's what I'm screaming, brutha! I'd need a thousand light bulbs for that! That's why I ask because they seemed a bit crazy to me!

Btw, that's right, though, right!? I mean the amount of lumens needed for that 24 square ft area!? 168,000!? I guess I'll start reading into HID bulbs!

Thanks for the quick reply!~

I ran a 600W hps in a 4x4 - that's less than 4000 lumens/sqft - and yielded about 1 ounce/sqft. That's definitely good enough.

7000 would be premium levels of light. I think you'd be very happy with two 600W hps in that space!

 

[Hosebomber]

This is broken down a bit better in those first 2 post, but you want to light the area of your grow. Lumens is a poor measurement of light for plants because it is skewed to the worst color output for plants. For 24 square feet you want ~1200 watts of HID or 1600 watts of CFL lighting.

Depending on the shape of your grow area 2 600 watt HPS or three 400 what HPS lights would probably be optimal. There is always the LED option that will cost more up front but less in power usage.

 

[comedian]

Thanks for the input, HB! I've considered a few things and researched a lot more, and I've decided that the HID bulbs are a better option!

 

[comedian]

Alright, folks! I think this may be my last question on lights, lol, but here goes . . .

I found some 300w CFL bulbs! The box says "4,200lm," and that's all! What confuses me is this thread says that CFL bulbs put our between 50-70lm per watt! My question is:

Let's say that I have a total of 8 300w CFL bulbs (a total of 2,400watts), and a 10 sq.ft grow area! This leaves me with two options:
Option 1. I listen to the box that says I have a total of 33,600lm (4,200x8) which gives me a total of 3,360lm per sq.ft.!
Option 2. I listen to the thread that says I have a total of 120,000-168,000lm (excessive I know-just an example) which gives me between 12,000-16,800lm per sq.ft.!

So which is it!?

Sorry for being so long winded, but I truly believe that this is the climax of my lighting questions, lol! AND, of course, thanks for any input or expertise!

Take care, all!

 

[Graytail]

The difference is the way CFLs are rated. The manufacturers like to print "equivalent wattage" on the box, which is what your 300 refers to. Those bulbs only consume about 70 watts, which is what we're referring to.

You're fine as long as you stick with lumens. Try for 3000 to 5000 per sqft - 30,000 to 50,000 lumens total.

But ... that's gonna cost you $200+ for bulbs, sockets, etc. A 400 watt HID would be cheaper and would perform much better for flowering.

 

[Hosebomber]

Again, this question is asked and answered in the first 2 post. DO NOT use lumens as a measurement for lighting your grow area. For a 10 square foot area you want at least 500 watts of HPS lighting for flower or 650 watts of CFL. This is the actual power draw of the bulb and not the equivalent rating. If you are stuck on the lumens and have no interest in reading the original post of the thread, you want ~ 7,000 lumens per square foot.

 

[comedian]

The difference is the way CFLs are rated. The manufacturers like to print "equivalent wattage" on the box, which is what your 300 refers to. Those bulbs only consume about 70 watts, which is what we're referring to.
You're fine as long as you stick with lumens. Try for 3000 to 5000 per sqft - 30,000 to 50,000 lumens total.

But ... that's gonna cost you $200+ for bulbs, sockets, etc. A 400 watt HID would be cheaper and would perform much better for flowering.

Thanks for the quick reply!

So you say to stick with the lumens, right! So is the number printed on the box right (4,200lm per bulb)!? This would make option 1 from my last post correct!?

 

[Graytail]

Thanks for the quick reply!

So you say to stick with the lumens, right! So is the number printed on the box right (4,200lm per bulb)!? This would make option 1 from my last post correct!?

Heheh, well, Hosebomber is correct - lumens differ between light sources, so it's incorrect to compare them directly, but for your purposes, it'll work. The 4200 number is correct for a 300 watt equivalent CFL, yes.

5000 lumens/sqft is adequate and 7000 is better.

 

[comedian]

Alright, guys! I know HB is getting upset with me, but let me explain what's going on! I decided to use HPS bulbs because it's my best option! Now the problem here is that my Lowes/Home Depot only has 400w HPS bulbs but the male part you screw into the female part is larger than your normal bulb! I've talk to a lighting expert, and me told me that the ballast for the HPS bulbs have to be mounted!

I really don't know where to find a 600w HPS bulb that fits into regular light fixtures! Any advice!?

I'm about to hit up youtube . . . .

Edit: looks like I'll be needing a ballast!

 

[Graytail]

. . . .

Edit: looks like I'll be needing a ballast!

Yep, you need a ballast for MH or hps. The whole setup (ballast, bulb, reflector w/socket) is pretty cheap online. I got a cheapie and ran it a year with no issue at all. You might get too much heat with a 600 watt in that space, though ... might want to consider 400 watt.

 

[Graytail]

It's my turn to ask a question of you, Hosebomber.

I've been considering expanding my LED lighting, and I've been comparing PAR grids and area coverage, etc. I find that my one 540 watt panel doesn't have much of a spread. At a 24 inch height, its off-center PAR drops 40% to 400 umols. So it really only has effective PAR in a 2 foot square/oval. The solution for my 4x4 is to add another 100 watts in each corner. If I'm reading the grids correctly, that should get me 500+ umols across the entire room at 24 inches.

At what intensity do we start overloading the plants? How many umols is too many? I see growers blooming large plants under 1000 umols now.

 

[Hosebomber]

Cannabis has the ability to use/process as much as 1500uMols (this is the highest amount tested). Temperature, quality of light, and CO2 units can all have an affect on this though.

 

[Icemud]

It's my turn to ask a question of you, Hosebomber.

I've been considering expanding my LED lighting, and I've been comparing PAR grids and area coverage, etc. I find that my one 540 watt panel doesn't have much of a spread. At a 24 inch height, its off-center PAR drops 40% to 400 umols. So it really only has effective PAR in a 2 foot square/oval. The solution for my 4x4 is to add another 100 watts in each corner. If I'm reading the grids correctly, that should get me 500+ umols across the entire room at 24 inches.

At what intensity do we start overloading the plants? How many umols is too many? I see growers blooming large plants under 1000 umols now.

I've found this common on all the LED's I have tested so far, they have excellent intensity just below the light (within the dimensions of the light) but more than 1' outside the direct overhead lighting, the lighting drops off quite a bit. I have found with LED it seems that more panels with less wattage is better than 1 large panel with lots of wattage. All of my different brands of LED do this, some carry the footprint better than others but they all drop off quite a big outside of a 2'x2' area for the most part. I think you are on the right track with more lower wattage lights to help extend the footprint.

As far as what I have read, cannabis should have at least 500 umol (at bottom of canopy) for best optimal lighting, meaning the tops are receiving much more than this. Hosebomber is right that plants can receive up to 1500 umol or so, before it starts negatively affecting photosynthesis rates (unless temps are ideal and supplemental co2 is added). Generally you should have a good 500+ umol across the entire footprint of your grow area for ideal conditions, as far as my research has showed.

A great way to look at plant lighting (and in my opinion, one of the most accurate) is DLI or Daily Light Integral. Basically this says that cannabis plants need 22-30 moles per day of light. Now the Umol that this translates to is defined by the length of the daylight period, hence why vegging plants need less intense light, and plants under a 12/12 schedule need a much higher umol. Basically it goes like this...

DLI requirement of 22-30+
(255 Umol - 347 Umol) PPFD on 24 hours daylight schedule.
(383 Umol - 371 Umol) PPFD on 18 hours daylight schedule.
(510 Umol - 694 Umol) PPFD on 12 hours daylight schedule.


Now these numbers generally are measured from the bottom of the canopy per my research, as well as how lighting specialists measure for greenhouses and commercial agriculture. Hope this helps ya out!

I would say just make sure to look at the PAR charts/over footprint to determine which lights will give you the footprint you are looking for, above 500 umol at the distance you are looking to hang them

 

[Graytail]

Excellent answer, Ice!

DLI is a great measure, and thanks for doing the math!

 

[ronnie6690]

Great info Ice + reps.

 

[McCdive]

Yes
Try starting Here How to Grow Marijuana - Everything You Need to Know!
The rest is based on budget space and need

I looked and looked and couldn't find anything on CFL and LED combination lighting pros or cons. Thoughts?