Light per square metre/feet for growing plants

[Leo_dean]

Hi, im considering getting into indoor growing but im having trouble grasping the idea of LED lights, i understand its not a light to plant ratio but what watt light would i need per square metre? and how many plants could i grow in a square metre?

sorry for the noobie question , any help would be appreciated

 

[Hugo Phurst]

Not a noob question.
Watts per plant is kinda a thing, for example when I used CFL's the rule was 150w min for 1 pant and at least another 50 for an additional plant.

A 315w CMH would cover m² nicely.
You can grow a whole bunch of plants in a square meter or just one.

 

[Frank Cannon]

400-500 w QB or H influx strips will be very tasty.

 

[Leo_dean]

So would it be overkill just to buy a 600w led light or would I only need a 300w? I’m pre keen to stick to LED for the power Efficiency. Thanks heaps guys I’m looking at eventually growing around 6 plants ish so I just don’t wanna buy a weaker light then have to buy a bigger one later

 

[Chip Green]

Time out for a moment.
Now, you do understand, that not all LED are created equally right? That some "600w" lights, are not actually what they claim? Furthermore, the term "Full spectrum" is actually a complete misnomer.

 

[Hugo Phurst]

would it be overkill just to buy a 600w

Nope

 

[TintEastwood]

...read up on watts per square foot/meter

https://growace.com/blog/how-many-grow-lights-do-your-plants-need/

Recommend....resist that urge to buy any Led, until you do your homework.

 

[Renfro]

These are the numbers I use when planning a grow.

50 - 60 watts per sqft with HPS

35 - 40 watts per sqft with CMH

Cheapo LED 50 watts per sqft

Quality LED 35 - 40 watts per sqft

 

[AlaskaRob]

Take a serious look at a dual bulb chm light! You can run one bulb at 315, or both for 630w! I hear people saying they're expensive, but I got mine new from Amazon prime for about 220. Bulbs were bought seperate, but my local grow shop got me into two Phillips elite bulbs for about 85$ each. I'm in a 5x5 tent myself. Chm at 630w is higher par readings than 600w by a few hundred at centerpoint. No bullshit. The heat is much less than 600w hid lights of other tyoes also. Ambient temp out side of tent is 73 usually, and my 6" AC infinity keeps the temp at about 77 all DAY during my veg cycle. Yes, i grow during the day, not night. Only time i have access to my remote site.

 

[Purpsmagurps]

i have 1kw of qb over 9x6

 

[Renfro]

Take a serious look at a dual bulb chm light! You can run one bulb at 315, or both for 630w! I hear people saying they're expensive, but I got mine new from Amazon prime for about 220. Bulbs were bought seperate, but my local grow shop got me into two Phillips elite bulbs for about 85$ each. I'm in a 5x5 tent myself. Chm at 630w is higher par readings than 600w by a few hundred at centerpoint. No bullshit. The heat is much less than 600w hid lights of other tyoes also. Ambient temp out side of tent is 73 usually, and my 6" AC infinity keeps the temp at about 77 all DAY during my veg cycle. Yes, i grow during the day, not night. Only time i have access to my remote site.

Why not just get a DE 600 watt CMH bulb and pop it on a 600 watt HPS ballast? Thats the ticket. One can even run a HPS bulb if they want. I have one running on a sunsystem 1kW HPS ballast dimmed to 60%.

 

[AlaskaRob]

Hugo is correct that a 315w chm would do nicely. I only suggested a 630w 2 bulb setup because you may want to up your tent size later. And I must say, 630w does incredibly well in a 5x5! I have 6 plants in mine, but plan to cut one down I to clones when I flip the lights this weekend. They're just too damn big at this point.
Besides, the penetration of a chm is far deeper than an LED anyday. I believe LED is around 12-14 inches? Could be wrong. Either way, chm penetrates the canopy 24-30 inches! Definitely something to consider when working with a small space like a tent I think.

 

[AlaskaRob]

The problem for Leo's situation would be that in his space more than 315w chm range of par would just be overkill imo

 

[AlaskaRob]

Smh to run properly needs a low square wave frequency. Putting a true smh bulb in an hos ballast could end in disaster I fear.

 

[AlaskaRob]

Sorry, I meant cmh. Damn autocorrect is my nemesis these days

 

[Renfro]

Hugo is correct that a 315w chm would do nicely. I only suggested a 630w 2 bulb setup because you may want to up your tent size later. And I must say, 630w does incredibly well in a 5x5! I have 6 plants in mine, but plan to cut one down I to clones when I flip the lights this weekend. They're just too damn big at this point.
Besides, the penetration of a chm is far deeper than an LED anyday. I believe LED is around 12-14 inches? Could be wrong. Either way, chm penetrates the canopy 24-30 inches! Definitely something to consider when working with a small space like a tent I think.

I have a 630 running next to a 1kW DE HPS and its just a little behind growth wise, maybe 10 - 15%. So it's close, I have a test run going this run to see just how close. My "foot print" is setup at 4x4 feet for each light.

 

[AlaskaRob]

Electricity consumption, PAR, CRI, lifetime of the bulbs, and heat output being considered? That's how I had to make my choice in the end. And I really liked the versatility of a dual bulb fixture that can also just run on one bulb. I am fearful of constantly buying new equipment and ending up with a bunch of piles of stuff i no longer use. I work with small spaces and a reasonable budget to keep myself in check.
Digital ballasts, I've been told, can have electromagnic interference for phones and such. All things considered, I just had to go with cmh. Although, in hindsight, I wish I could've tried a bigger hood for wider coverage to be honest. I hear that cool tube reflector' s glass tube interferes a small amount with light intensity that reaches the canopy, but I REALLY like the idea of pulling cool air in and out of the tent over just the bulb. I'm dying to try co2 next time.

 

[AlaskaRob]

AND you're cheating just a little by using a DE bulb, renfro. lol
Besides, I bet you'll have to change that DE bulb for another bulb spectrum between veg and bloom? Whereas cmh bulb from Phillips can do both.

 

[Frank Cannon]

4 x QB 96 and 2 x 320 drivers.

Done!

 

[AlaskaRob]

Frank, I keep seeing QB mentioned in other threads. What is it? Sorry, I'm still fairly new. I just did 6 months of research before making my choices for my setup. I'm going into week 5 of veg after a hiccup with some serious heat issues. Didn't realize my ducting came loose from the exhaust port near window and was recirculating the ambient room air with my tent! Ambient room twmpmoutside of tent is 73, needless to say spikes of 84 scared me a bit and I wanted to give an extra week or two to make sure everything was back inline before flipping the lights for bloom.