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Light Height: Fixed vs Adjustable, HID and LED

GeOMaTTiC

Well-Known Member
There are several posts regarding the optimal distance from the plants that the lights should remain, however, I am after some different information.

Does anyone in here grow with their lights set a fixed height?

Do you keep the plants on the floor, and just let it grow towards the light? Or, do you have something to bump it up higher so it is much closer?

I am curious as to what some have tried, as I am thinking I may do it in my shed. That way I can have the lights cooled with outside air in a more durable and rigid fashion, and not having to worry about the flexible ducting getting ruined or in the way.

Technically it will work, as it is still providing light, just how well it works is the question.

********Inner thoughts to myself********As the plant grows, the quality of light it receives will increase, which if I remember correctly, being closer is great for flowering. Perhaps it is only something that can be done with HID, and the really good LED's, not what I have currently************
 

Stunned

Well-Known Member
there are general guidelines as to where your light ought to be given the stage of the plant's life
and they tend to grow at different speeds and heights even within the same species
I have one on a bankers box and another on a couple of old encyclopedias lol
it's all about trying to keep the canopy more or less at the same even height
of course, having a light fixture that can be adjusted is preferable, and honestly not hard or expensive to do
 

Remystemple

Well-Known Member

GeOMaTTiC

Well-Known Member
I am not trying to say the people here are completely wrong, just seems that they are also not completely right. More than one way to skin a cat.

They are in the business to make money, so I do not see them skimping on a cheap pulley system to save a small chunk of change.

I had decided I will build my shed with the lights at a fixed height anyhow, and test two plants. One will be on the floor, and the other will be raised (via wood crates) to the "optimal" distance between light and plant.

Will not be until next winter, so plenty of time for others to try it first, if they choose to try it out.

Of course, I will document all findings. It may be minimal change, might be major. That is the beauty of trying new things.
 

Remystemple

Well-Known Member
I am not trying to say the people here are completely wrong, just seems that they are also not completely right. More than one way to skin a cat.

They are in the business to make money, so I do not see them skimping on a cheap pulley system to save a small chunk of change.

I had decided I will build my shed with the lights at a fixed height anyhow, and test two plants. One will be on the floor, and the other will be raised (via wood crates) to the "optimal" distance between light and plant.

Will not be until next winter, so plenty of time for others to try it first, if they choose to try it out.

Of course, I will document all findings. It may be minimal change, might be major. That is the beauty of trying new things.
I don't think it comes across that you're saying everyone in the forum is wrong. it's a damn good observation and question. and might be some info to learn here that could be very helpful to a lot of people.
 

GeOMaTTiC

Well-Known Member
To me, as a new grower, kinda seems like I am. However, I took Horticulture in college, and we never discussed height of lights. The greenhouses we worked in had their lights well beyond 4 feet above the plants. That being said, it wasn't for cannabis.

And that also being said, we (the toking students) did sprout some cannabis seeds in the back corner, in the propagating table, and they grew remarkably fast. Sprouted over the long weekend (Fri-Tues), and was 3 inches by Tuesday afternoons classes. Took it home and got in major shit from my folks lol.
 

SmokeSara

420 Sponsor
Different light hangs differently; HPS/HID are hot, so you need to hang higher, I watched a youtube video before that they mentioned usually more than 30'' above plants, so that plants won't get bleached, while get enough coverage;
But for LED grow lights, they are not that hot, they will need to hang lower, during flowering, 12~18'' will help you get great results;
As to greenhouse, usually greenhouse growers are using lights for compensation for sunlight, so they usually hang the light higher. :Namaste:
 

GeOMaTTiC

Well-Known Member
I keep my 630 cmh lights at about 48 to 60 inches above my plants.
My 315's at about 30 inches.

Works well for my room...View attachment 1696868

This is from my last grow.
Just harvested a pound from 2 plants and haven't weighed the other 8 yet.
Excellent setup. Perhaps I may look at a CMH light, instead of a HPS & MH combo...just don't like the price difference.

Do they run any cooler, or about the same?
 

Bigjake8

Well-Known Member
I got a 315 CMH in a 3x3 and it gets about 60 % of what my 1000 hps does in a 5x5 that's same strain and nutes mix but it's in a air cooled reflector that's why I'm interested in this I just rebuilt the ballast and bulb so I gonna give it a fair shot by opening it up and raise it as high as I can and se what happens
I was reading a article on how much light you need and didn't make no sense to me guy said you could light a 20x12 with less than 4k watts with his formula he took square footage and divided by 4 then used the 60 watts a square foot I don't know who was too high him or me
 

GeOMaTTiC

Well-Known Member
Holy crap, that's some impressive growth. Nice job. Looks like being far away doesn't hurt as much as previously thought, good to know.

Still going to go with MH/HPS combo in the shed, as it can do with the additional heat during the winter.

I will try out a CMH for the basement tent.

I still love LED, so my bedroom tent will remain blurple......for now
 

Remystemple

Well-Known Member

TurboBucket

Photo of the Month: Jan 2019 - Plant of the Month: Feb 2019
The biggest reason you see really tall lights in greenhouses/warehouse grows is because they can. The father a light is away the more it will spread out. And conversely reflect deeper into the canopy. The caveat is that it loses intensity so you need more lights over a given area to reach the same level of light. They can also more easily afford to purchase and run as many lights and cooling equipment as they like not always the case for a home grower.

This is why you see so many people trying to run their lights as close to the canopy as possible their trying to hit that 1000 par Mark without breaking the bank.

Light distance is kind of an old metric, when everyone ran the same bulbs and ballasts it was easy to say "set your light at 36in for veg." They were able to communicate par levels without actually knowing them. But now different lights produce drastically different par levels at drastically different heights. It's all about how much energy your plants receive from the lights. Quantum meters read how much Photosynthetically Active Radiation (par) falls on an area this is the energy your plants absorb to grow. But I'm sure you knew that from college.

Basically the father away you can keep your light source and maintain the needed par levels the better. :thumb:
 

sativuhhh

Well-Known Member
While the HPS/MH lights are pretty much the same and heights figured out, LED's can be all over the board in distances needed depending on type and brand and intensity since the heat likely won't be the limiting factor.

The other difference I think on those big grows with the calculated light coverage may not be quite fully maximizing every bit of possible output from the plant vs having a warehouse full of plants that produce 80% but is easier to mange at scale vs a lot of our smaller personal grows on here that get a lot more attention and tailoring of lights and heights to the single plant or two scale.

Just put the lights on some ratchet hangers and you can easily change heights as well, in a shed or anywhere. Also depends on if you are letting it go wild or are topping and training and trying to keep low or if you want it to climb up to the lights.
 
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