Assistance With Light for 4x4

I am super duper confused about sizing lights. I’ve heard the hard and fast rule of 32 - 35 watts per square foot but that doesn’t seem to apply to LED’s?

I’ve also been looking into PAR which seems to be the best way to determine how much light plants need, but PAR changes based on how close the light is to the plants. It doesn’t help that manufactures aren’t honest when it comes to coverage. Is anyone able to help clarify without getting too deep into the weeds? I’ve looked it up online but I’m still confused.

With all that said I bought this light for my 4x4 grow space:

I plan on growing at most 5-6 plants at one time. Will this provide enough light during the flowering stage to promote healthy growth or will I need to get another light? I really appreciate the help.



Smart to ask before buying anything.

That light will be great. You might want to look at HLG. Same quality or better, and great customer service.

The light you’re considering might actually be more than a 4x4 needs, but it won’t hurt. Just my opinion, but maybe a 4x6 tent would be better for 6 plants.


@Crumb93 You won’t get 5 to 6 plants in a 4x4. Not unless you want small amounts of the green herb or growing Autos.

Here is a picture of my 4x4 with 4 Photoperiod plants and not enough room at all.

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Ok this is good stuff. For my 4x4 I’ll want to stick to 3 plants max then.

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I’m going to run a single plant in a 15 gallon fabric pot after these 4 finish. One will definitely not produce like the one. That is ok as long as the one plant gets a nice yield.

That is a good choice to run only 3. You may want to look at the HLG lights for your 4x4. I run 2 HLG 260xl Rspec lights aka 4 QB’s and was definitely worth the price tag.


Fair enough. 3 plants using ScrOG should be fine though right?

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Long as they are the same strain you could pull it off. I can’t remember which member posted that little piece of information.

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Very nice. I appreciate the input.

That light would work by the way. But for like $140 more you can put in two HLG 260xl Rspec lights. This is the lights @dbrn32 said would be a good choice for a 4x4. He is the light guru so I took his recommendation seriously and bought 2. Best investment ever. :+1::+1::+1:


Others are already helping you with choosing an LED light, so I’ll just address this.
It is “35-50 watts per square foot” and only applies to HID lighting. It’s definitely not a hard and fast rule even for HID, but it’s a decent general guideline to go by. For LED lighting it’s really PPFD that matters.

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If you figure ~2’x2’, that allows room for a dehumidifier/humidifier/space heater, should the need arise.

That’s not to say you couldn’t get away with scrogs that fill out the entire tent, so long as there’s room below the canopy and inbetween containers.

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That’s misleading based on single point measurements. Moving light doesn’t change amount of light fixture emits. So if you lower fixture to increase intensity level in the middle you are losing intensity somewhere else. Most likely at edges and corner of your space.

Look for a fixture that you can find total flux (ppf) not ppfd.


Rapid LED makes a nice kit for a 4x4. If you like COB’s.

Man that is nice looking!

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The truth is you can grow allot more than that in that space if you grow a “smaller plant” style of sea of green but most people grow, including myself along with mrpeat, “average” size plants.

If you grow an average size plant, which is what will probably be the easiest, about 4 plants will be your max.

I currently have 5 plants in a space that size and it is wall to wall, But four of them are in 5 gallon buckets. If I downsized to three gallon it would be easier to do


@TDubWilly My wall to wall 4x4. The tallest plant is already past 5 feet tall. This is a older picture.

I will never ever grow 4 plants in my tent again. Especially how I prefer a monster plant than 4 small ones.

Sorry I can’t upload photos since the service for it just isn’t there. But go to my Toilet Bowl Seeds thread.

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Do you think a new grower would benefit from larger plants, due to the added robustness/resilience that comes with a big plant? Are smaller plants harder to read?

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@KeystoneCops It’s how I rolled into growing. I started my first crop that turned one into a beast. Then a few subpar crops since I had 8 plants in my 4x4.

Then my first real outstanding crop was my Blue Dream at 3.32 z’s dry and my GSC Beast was at 8 z’s dry.

Now this crop I will get a great yield.

Personally I’d rather have two big girls than 4 small ones. Especially if you train them. I think it would be harder to give enough nutrients and not go overboard on a small plant for a first time grow.

Now a big plant will give you a good cushion as they need more.

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I prefer medium sized plants. I currently have 8-10 in a 4x4. Smaller plants you can flip quicker, larger plants take longer to veg, but it comes down to growers preference.


I’m not suggesting larger plants are the most efficient route. I’m just curious if they’re the best learning tool for new growers.

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