Double light = double yield ??

Hi riu crew,
just thinking about my second grow. My last grow I grew 12 plants under 200w led lights and yield 20g per plant in 1 gallon pots. This grow I'm looking to double the light but realistically what will the 100% extra light yield?? Using the same 1 gallon pots. Appreciate any advice.

provided u have space your yield will be about twice as much. Watts = weight. Get 2 gal pots

you'll have to veg longer too

blakjak said:

My last grow I grew 12 plants under 200w led lights and yield 20g per plant in 1 gallon pots. This grow I'm looking to double the light but realistically what will the 100% extra light yield??

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You want to think in terms of watts per sq. ft. And, actual watts used, not the LED fixture's theoretical max (i.e., 3w x 60 bulbs is 180w theoretical. But, it's common to run LEDs at about 60%, and a Kill-A-Watt meter will show 120w at the wall.).

With inexpensive Chinese lights (or rebranded lights sold at a premium), you want 30w to 40w sq. ft. Some users of TopLED's Mars II light run 50watts sq ft.

With more expensive lights using geniune Cree bulbs (chips), you could do 20w sq. ft. For example, the Area51 RW-75 uses 75w and will cover almost a 2x2 space in flower.

I use two Blackstar 135w (88w actual) UFOs in a short 2x4 tent for two autoflowers. That's 22w sq. ft. I think Blackstar is more of an over-priced Chinese import. But, it goes to show how vertical space places a role too. If you're going to grow smaller plants, you need less watts per sq. ft.

More light will undoubtedly help unless you're at a ridiculous level already. But, at some point it becomes diminishing returns. For example, using T5HO, Frank/Rosenthal say 40w sq. ft. is optimal, beyond 50w sq. ft. is diminishing returns.

You should expect LEDs to be more efficient. So, you'd think 20-30w is the optimal range. But, unlike T5HOs, there's a lot of variability in efficiency depending on whether top bin LEDs are used. 30-40w might be the optimal range for less efficient (Chinese import) brands.

You could supplement a couple plants with CFL and see how much difference the added light makes compared to the unsupplemented.

Cheers guys appreciate it. Az u are a legend! I'm taking a little time to digest all that info. Forgot to mention I was growing auto's. The lights I'm using atm are 240w vipar Led s from eBay. It says total power is 100w. Anyway I'm pretty happy with the results. 20g a plant on 1st grow using 2x 240w, tbh was more than I expected given the space. Anyway I'm looking to upgrade to a 4x8 tent using two vipar 1000w led s which have a total power of 510w. I'm thinking that is actual watts. I believe for sq ft that's about 31w. Also I'm looking to heed purple hazes advice and go for 2 gallon pots. So I'm looking at 32 plants in 4x8 which I guess should yield around twice as much the in comparison to the previous yield given the additional light and bigger pot size ??

I grow autos starting and ending in 3gal containers. No transplanting. They're a little slow taking off (filling out the container with roots). But, they take off after 3 weeks. I'm pretty good at transplanting photosensitives. I should try starting autos in 1gal and transplanting to 3gal. But, the only difference I can see it making is better wet/dry cycles for a younger plant in a smaller container. I struggle with long wet/dry cycles of a young plant in a 3gal container. Trying to get more nutes in there while not overwatering. That first 2-3 weeks is complicated. But, with an auto's fixed lifecycle, I'm reluctant to transplant and lose a day or two from shock.

Regarding your lights. A lot of people like Vipar. I don't think they use top bin LEDs. Probably just a rebranded Chinese light with some spectrum the people at Vipar like. I think you'll need more wattage than you would with Area 51, Onyx. But, with smaller autos you need less wattage. Especially if you're keeping them short through scrog. Probably 20w to 25w sq. ft. using less efficient chinese imports. I don't think you need more than 35w sq. ft, and if you went that high, it's going to be diminishing returns. (In a 4x8 tent you can always group lights to give one area more light and see how those plants differ. Whether more light is worth it.).

Also, I'd recommend more smaller LED fixtures than two monolithic. You'll get better coverage/diffusion. And, when (not if) a light fails, it won't be catastrophic as losing half your lighting with two big 4x4 coverage lights.