Optimal spacing for SOG

[IslandColas]

Does anyone have an idea what the optimal spacing is for sea of green clones veged a week from rooting? I know DrPhoton likes SOG and is a efficiency expert, maybe he can chime in.

[DrPhoton]

It depends on your light source. Ideally you want to match your light source to your plants, or match your plants to your light source. Of course when you are just starting out with young plants, you initially have a smaller surface area of leaves. So you ideally want to match your lights at this stage. This would be using a light source that matches the surface area of space currently occupied by your plants.

For example here is the optimal lighting for several sizes for gas discharge

1x1 Fluorescents or low powered LED.
2x2 250 watt HPS/MH
3x3 400 watt HPS/MH
4x4 600 watt HPS/MH

If you are using a large light source initially to start your plants off, then spread them out just enough so they are not crowding. That way they have their own source of light and do not have to share. No point wasting free energy that would otherwise be wasted through radiative and reflective losses.

This is why the more plants you have for a sea of green (to a certain point) the faster and more efficient it is. As you fill the horizontal space more quickly and capture more light at the same time. Increasing the light utilization efficiency.

Might want to check my article out on using light efficiently.

[IslandColas]

I’d be putting this light in a 2x2:

LED Grow Light 1500W, Dimgogo Triple Chips Full Spectrum Grow Lamp with UV&IR for Greenhouse Hydroponic Indoor Plants Veg and Flower All Phases of Plant Growth (10W LEDs) https://www.amazon.com/dp/B07B62PB28..._OzFGBb92C714E

how many week old clones should I put in that space? As many as I can without crowding?

DrPhoton

[DrPhoton]

A sea of green is only considered a SOG when you do not have to top your plants to fill in the horizontal space. If you are having to use any sort of plant training then you are technically not operating a sea of green.

9 plants in a 4x4 is what i consider the bottom end of technically SOG. And the top end being 36, any more and the gains are very minimal and possibly decline due to added complexity. 25 is a good medium ground.

Here are the plants per square foot for 4x4

1 plant per 1.8 SF = 9 plants
1 plant per 1 SF = 16 plants
1 plant per 0.64 SF = 25 plants
1 plant per 0.44 SF = 36 plants

Here are the plants per square foot for 2x2

1 plant per 1 SF = 4 plants
1 plant per 0.44 SF = 9 plants

The reason there are only two choices for 2x2, is because of symmetry. You ideally want to have a uniform ratio that matches the room that it is grown in. Which only allows 4 and 9 plant configurations as they fit between the 1.8 - 0.44 SF range.

Hope that makes sense ^.^

4 plants should be plenty for a 2x2 space if you are planning to grow them out all the way in that space. Thats like having 16 plants in a 4x4. If you are however using the 2x2 just for vegging and moving those plants elsewhere later on, then you can do 9 plants. Saying that you could possibly get away with 9 plants for a full grow in 2x2, but it would be tight ^.^

Any further questions feel free to ask.

[IslandColas]

It’s got a diagram showing par at multiple distances to help. Assuming these are correct.

[DrPhoton]

Unfortunatley none of those measurements help with much other than what height is best to place the light source from your plants. Using approximate calculation, i used the wattage and average LED efficiency to get the photon flux. Which is about 350umols. Equivalent to a 250watt HPS, so should work nicely for that 2x2. May be even a little over kill actually as the averaged PPFD would be around 900umols. So be mindful of the height you place that fixture.

[hycheese]

DrPhoton , if my SOG were in an Egyptian pyramid 500' tall by 700' wide and using animal fat for lighting could I achieve the umols needed using mirrors instead? J/K I always love your concise and to the point answers.

[DrPhoton]

Just for a laugh, i tried calculating it.

For 700 feet by 700 feet, you would need a light source, or sources that provides at least 20,000,000 umols of photon flux. Now i couldnt figure out the formula for the volume of combusted fats required to reach that level of radiant energy. But if you could get that, you would definitely be able to work out what that would be and you would likely be able to grow under the suggested parameters. You would have to use diffusive mirrors however as typical specular types would not provide enough uniformity.