Lights and multiple plants question?

Rootbound420

Rootbound420

Well-Known Member
I feel like this may be a dumb question but do more plants equal less light per plant or how does that work? Example you have a 600 watt light run 2 plants 300 each plant. But if you run 6 plants your getting 100 per plant?
 
The idea of using wattage as a metric is N watts per square foot of grow space. The underlying idea/goal is that the entire grow space will be filled by the canopy of the plant(s) in the grow space.

Input wattage is only a rough metric. What drives crop yield is the number of photons hitting the canopy. A grow with a modest input wattage, say 30 watts/square foot, can have a great yield if the tent is full whereas a high powered light that's hitting a plant that fill just a limited amount of the grow space is "wasting photons".

The number of plants does impact yield per grow as well as yield per year. If you grow many small plants and cover the grow space, you might get four grows per year whereas, with larger plants that don't quite cover the grow space, you'll get a lower yield per grow and, since they take longer to grow, you might get only three crops. That's not a big deal if you're a personal grower but something to think about if you're growing for others or if you're in the biz.

In terms of input wattage, 30 wats/sq ft is "modest", my preference is for 40 but I will be upping that to 55 watts/sq foot starting with my next grow . The reason for that is that light is how a plant makes food ("nutrients" are not food for a plant - they're akin to vitamins and minerals) and, up to "the light saturation point", the more photons hitting the plant, the larger the crop and the higher quality of the crop, in terms of the amount of secondary metabolites as well as in terms of the ration of flower to plant mass.
 
Appreciate the response! Very informational. I am right around 50 watt/square foot. Reason I asked is because I filled the tent slap full this run, just harvested and have enough stock now for about a year so I want to dial back and just focus on 1 plant harvest once a month so I can gift to family and friends. Save everyone some moolahh!
 
Rootbound420 said:
Appreciate the response! Very informational. I am right around 50 watt/square foot. Reason I asked is because I filled the tent slap full this run, just harvested and have enough stock now for about a year so I want to dial back and just focus on 1 plant harvest once a month so I can gift to family and friends. Save everyone some moolahh!
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50 watts is great!

"1 plant harvest a month" - that sounds like a perpetual grow and that means autoflowers, right? I think it's correct to say that if you grow autos in small containers, they'll end up maturing quicker than if they're in a large container but I grow hydro using a 35 gallon res (hold 28 gallons of nutes) and my grows take 110+ days. :-(

At 50 watts you will have plenty of light available. I'd recommend a light meter so that you get your plants to >= 1000µmol level.
 
Delps8 said:
50 watts is great!

"1 plant harvest a month" - that sounds like a perpetual grow and that means autoflowers, right? I think it's correct to say that if you grow autos in small containers, they'll end up maturing quicker than if they're in a large container but I grow hydro using a 35 gallon res (hold 28 gallons of nutes) and my grows take 110+ days. :-(

At 50 watts you will have plenty of light available. I'd recommend a light meter so that you get your plants to >= 1000µmol level.
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Yea Im growing autos right now. I use 3 gallon rains science pots. Mine usually go from 75 to 100 days leaning toward 75 depending on the strain. And I am attempting perpetual yes around 1 harvest a month give or take a few weeks. I did a large grow that just ended 8 plants so I have stock for awhile now it's time to play around!
 
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