How much light is to much?

[jwar]

I recently changed from a 600w hps to 3-450 watt leds. My understanding is that the true power of led light are what they actually draw power wise from the outlet. These leds draw 200w at the outlet so they should be equal in watts. My space is 2'x4' 8' tall. I never had any problems with the hps lights. Are the 3 leds to much for this area? my last grow turned out to have 100s of seeds. I only use female seeds from a good source and have never had a male in 10 years. I have been told light stress would be a possible reason for this. The buds were big and beautiful, tasted great and work good. thank you

[KingKush]

Light stress can go two different ways depending on if it's too much or too little. In my situation, too much light causes physical damage only at the site. Just because my tip top cola bleached or a few leaves went crispy doesn't initiate hormonal changes inside the plant. It thinks survival is easy with all this sun. I'm always bordering on "too much" that's just the way I was taught to grow. "If you are not getting a little negative reaction you don't have your lights low enough" - said 1 person.

On the flip side, I get hermaphroditing with NOT ENOUGH light. So perhaps your ladies thought survival would be difficult with the lack of light. Hence the self replication maneuver. There's a big science with the spectral output of LEDs and then how PAR and lumens and lux are kinda different than HID bulbs.
All I can say is lower your leds until you just start to see a reaction going the wrong way and then back off slightly?
Cheers!

*edit: I read that you switched to these leds in week 2 of flower from your hps? Yea that would freak out any strain even stable ones

[jwar]

Thank you for your response. I think I'm going to accept the fact that the change in lights and late heavy pruning. I understand what you are saying about too little light being a possible cause and am hoping that the amount of light I have now will be adequate. Judging by the way one of the plants finished (doesn't smell as good, less production,and not so good to smoke) it was the one that took the most abuse and caused the others to put on seeds. Is it possible for one to hermie and affect the others?

[KingKush]

Yes it's possible for a single hermaphrodite flower to pollinate an entire crop. Even from your neighbor! Each pistil is designed by nature to act like a sticky magnet for pollen. Pollen floats in the air and travels well in the breeze. Even a little banana/ Nanner sticking out can seed out a crop especially if it can spit pollen in front of your fan.

[GroJimmy]

PAR value is what counts, the higher the better, all light has a PAR value, finding that value is difficult as most manufacturers do not provide this. My T5 54w bulb is about 100 par, where my 1000w DE HPS is 2100 par, a SPYDRx commercial LED is over 1500 par. Giving the size of tent, I would start with 2 lights and watch closely, if no problems add the third.

[Flockshot]

I need help understanding how much benefit PAR really means to results. With my HPS at 600w out of the wall, I get about .66 grams per watt. Companies like Viparspectra claim their PAR700 will replace my 600w HPS at only about 325 watts out of the wall. If results were equal, I would get 1.25 grams per watt out of the LED. I just don't see that happening.

[gdogfunkly]

This video shows a comparison of several LEDs and he discusses a bit about PAR: https://www.youtube.com/watch?v=-Or5Cx-fjOU

[Flockshot]

If watts out of the wall is a better indicator of what a grower can expect to get, we don't need manufacturer claims muddying up the waters.

[dontknownuttin]

Me ether but let us know what you discover.

[D.A.A.S.69]

You got 8sq, feet, your getting the same watts per sq.ft. as you were with the 600hps, except you should be getting better coverage with the 3 leds,.
Switching to leds didn't cause hermies, something else did.

[GroJimmy]

Photosynthetically Active Radiation (PAR) is the amount of light available for photosynthesis, which is light in the 400 to 700 nanometer wavelength range. PAR changes seasonally and varies depending on the latitude and time of day.
Photosynthetically Active Radiation is needed for photosynthesis and plant growth. Higher PAR promotes plant growth, and monitoring PAR is important to ensure plants are receiving adequate light for this process.
PAR values range from 0 to 3,000 millimoles per square meter. At night, PAR is zero. During mid-day in the summer, PAR often reaches 2,000 to 3,000 millimoles per square meter.

[DrPhoton]

PAR refers to the range of light that plants use, PPF refers to the total amount of PAR photons produced by a light source per second (μmol/s). This is similar to the Luminous Flux or Radiant Flux. Where all energy is captured from a source and quantified.

Check out my article on light metric systems for a better understanding on metric terms.

A cannabis plants maximum photosynthetic capacity is around 2000umols per square metre. But thats not ideal. Most plants will prefer around 1000umols per square metete. A 1000w hps will typically output around 1500umols per square metre. So this would likely be too much for a 4x4 tent.

Check out my article on light proximity for better understanding on plants and photosynthesis.