Too much light? WTF?

Been seeing lots of posts about plants getting too much light. How is that even possible? Full sun all day benefits a plant.

I realize most posts are regarding indoor growing, but still, how can artificial light be more intense than the sun? Is this more of a heat issue if the plants are too close to the light source?

obijohn said:

Been seeing lots of posts about plants getting too much light. How is that even possible? Full sun all day benefits a plant.

I realize most posts are regarding indoor growing, but still, how can artificial light be more intense than the sun? Is this more of a heat issue if the plants are too close to the light source?

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Mine got plain old fashioned cooked this grow from too much ppfd. By the time I had a lux meter and developed trust in it they had been getting over 1250 ppfd for weeks and bleached white on the top fans. Temps and humidity were great, 80-82 and humidity in VPD range. 700 watts was just too much light for full power in the early stages of flower. That's just what I've experienced using a newer more powerful light than the cob I had been using for years. I learned to respect these high power bar lights and boards and hopefully I'll get a better grip on it next run.

You ever got flash burns from welding?

As a benchmark, here's a measurement of full sun reading up to 2,500 mols PAR on an Apogee meter.

these new lights. it seems some strains can't even handle a lot of light...back in the day a plant could take all the light you could give so long as the temp was ok. not sure what's up with the light/strains today. so far, indicas are the ones giving me trouble. it is possible during my blurple grows last decade that i was getting some light sickness. thinking back, they always looked better just at light on. it was also the first time i bleached a bud/tip.

i am running under 250ppfd in week 3 of veg and this plant is not taking it. it's a shriveled mess after about 8 hours of light. the two other ones that showed some dislike for light in week 2 are acting normal now.

Thats

Splinter7 said:

these new lights. it seems some strains can't even handle a lot of light...back in the day a plant could take all the light you could give so long as the temp was ok. not sure what's up with the light/strains today. so far, indicas are the ones giving me trouble. it is possible during my blurple grows last decade that i was getting some light sickness. thinking back, they always looked better just at light on. it was also the first time i bleached a bud/tip.

i am running under 250ppfd in week 3 of veg and this plant is not taking it. it's a shriveled mess after about 8 hours of light. the two other ones that showed some dislike for light in week 2 are acting normal now.

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That's nuts. Ive been at 800ppfd since pop 14 days ago. I don't think I've ever had seedlings under 600umol/s.

They’re photons not brotons gotta watch out

obijohn said:

Been seeing lots of posts about plants getting too much light. How is that even possible? Full sun all day benefits a plant.

I realize most posts are regarding indoor growing, but still, how can artificial light be more intense than the sun? Is this more of a heat issue if the plants are too close to the light source?

Click to expand...

It's a lot of things. Leaf temp issues..IR..indoors if you are sealed and adding co2 you can use a lot more light with good effects but you can still have leaf temp issues etc. No matter what artificial light doesn't compare to unlimited root space and the sun. Outdoors you can fairly easily get 12-even 32 or more oz off a single plant. You want to know take a 1k watt hps or mh and put it inches away from a plant. Doesn't mean indoor isn't great it gives you other environmental control benefits as well as detractions. It's impossible to replicate everything about the sun esp once accounting for cloud albedo and dozens of more effects. Spectrum and atmosphere, intensity it's just not the same. I mean hell most of our innovations come from trying to replicate nature.

FirstCavApache64 said:

Mine got plain old fashioned cooked this grow from too much ppfd. By the time I had a lux meter and developed trust in it they had been getting over 1250 ppfd for weeks and bleached white on the top fans. Temps and humidity were great, 80-82 and humidity in VPD range. 700 watts was just too much light for full power in the early stages of flower. That's just what I've experienced using a newer more powerful light than the cob I had been using for years. I learned to respect these high power bar lights and boards and hopefully I'll get a better grip on it next run.

Click to expand...

Were you running CO2 ?

No, I just didn't get the meter until it was already getting light stress and then I didn't trust it that the canopy was getting 70-75K lux at the peaks. I should have had a meter to start out with and kept them under 50K lux. Only one plant really got toasty, the others did pretty well. I'm trimming the tops of the OG Kush that got it the worst right now and will be taking down the others over the next week.

I am currently having issues, but I believe it’s me not being used to growing bigger plants than usual, and I’m under feeding. Then when I try to bump it up I burn em. Typical noob shyte. I have to get used to the new lights. Find one I can really work well with & stick with it.
So far the SP6500 & FC4800 have been pretty cooperative with my slack.