"Light Burn" adjustments ... suggestions ... discouraged - please help

Plant Care Environmental Stress
#1

I am on my first grow and purchased a 2x2x4 grow tent with a PhatSlim Phantom One grow light. This is an Amnesia Haze auto flower growing in FFOF. It is currently on day 86 past germination transplant which occurred on September 20. Flowering began on October 14 (8 weeks into flowering, beginning the ninth week today.) I have been having a problem with “yellowing” leaves which was initially deduced to be “under nutrition.” The nutrients were being adjusted but yellowing leaves continued. Earlier on a forum member indicated “light burn” which indeed is occurring. The light burn is getting worse. I have raised the light to its highest possible position in the tent. Light schedule was adjusted to 16-8. (Side note: I misunderstood the light schedule early on using 24/7 for seedling and did not make “the flip” at flowering. The light schedule adjustment did not occur until three weeks ago.) I’m hoping I have not done irreparable damage to the plant because it is clearly still struggling.

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(I feel like a horrible parent!)

In as much as I intend on continuing to grow I purchased another outfit for the grow room. I purchased a 2x4x6 grow tent with a TSL 2000 grow light. I moved the plant into the new grow tent about a week ago but have discovered that I cannot raise the TSL 2000 very much higher than the other grow light was due to the Carbon Filter being in the way. It may be too soon to do so but I am not observing any improvement at all in the light burn and it seems to continue to worsen. (I don’t know if a plant will recover from light burn.)

Other than waiting it out and hoping for the best is there anything else I can be doing? The TSL 2000 has a light intensity adjustment for the various stages of plant growth. (Would lowering the intensity be a consideration?) I am beginning to see where the light burn is affecting the “sugar leaves” as well. Your feed back will be most appreciated and I assure you that do better on the next go round.

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I have read a little about “albino weed” and most definitely hope to avoid that! (Do you think that will be an outcome for this plant?) Thank you for your feed back and help!

#2

Looks like the plant is nearing the end of its natural life cycle.
They will begin to pull the the mobile nutrients out of older leaves and they will yellow and die.
In other words its just the natural end of the plants life.
It actually looks great. You should be checking the trichomes now and looking for cloudy & amber resin.
No worries mate, you did it.

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#3

Thanks a bunch for that bit of encouragement!!! But the burn on the end of the leaves; is that normal? The Trichomes remain clear at this time; will be looking for just under 50% or so (as much as I can gauge it never having done so before.) Thanks a lot man!

#4

I don’t see signs of light ‘burn’ (normally with LED’s it’s light bleaching) but do see signs of N deficiency and nute burn. Without knowing more about your setup it’s hard to say. Flower is maturing but not there yet.

Do you have a digital PH and TDS meter and do you use them? What are runoff numbers? Are you feeding?

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#5

Generally speaking, when you have light damage it’s not seen in lower parts of plant. I think your original diagnosis of nutrient issue was correct, or maybe ph lockout.

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#6

FFOF soil. Began adding FF “Trio” at 35 percent of feeding schedule recommendation three weeks after initial flowering stage began. An assessment of Nitrogen burn was suggested and N was discontinued about four weeks ago. A run off PPM test three weeks ago indicated 800 ppm. I was informed that ppm should be higher and the nutrient added were increased to 50% of FF recommendation (FFOF should have been sufficient to not use 100% of suggested feeding schedule.) A 6.5 pH has been maintained after nutrients are added to water throughout the life of the plant. Cal/Mag was also suggested (which I had not been using until two weeks ago.) Some posters indicate that Cal/Mag should be for the entirety of watering regimen; is this also your suggestion from experience (for when I begin my next grow)?

#7

“Nutrient lock out” I have maintained a pH of 6.5 after nutrients were added inasmuch as 6.0-7.0 was the acceptable range. Cut and paste what I replied to myfriends410: Began adding FF “Trio” at 35 percent of feeding schedule recommendation three weeks after initial flowering stage began. An assessment of Nitrogen burn was suggested and N was discontinued about four weeks ago. A run off PPM test three weeks ago indicated 800 ppm. I was informed that ppm should be higher and the nutrient added were increased to 50% of FF recommendation (FFOF should have been sufficient to not use 100% of suggested feeding schedule.) Cal/Mag was also suggested (which I had not been using until two weeks ago.)

BTW…you are the “go to guy” for lights, arent you! “How do you do?!”

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#8

I’m doing well, thanks! And you?

Your ph of 6.5, was that measuring what you were putting in or from runoff readings? It’s a little higher than I feel works best for me, but if you maintained 6.5 in and out should be plenty reasonable. Needing calmag is pretty dependent on what base nutrients you are using and at what concentration. A lot of people need it, but not everyone. Also worth noting that with reasonable base nutrients you shouldn’t need much beyond mid flower in a soil grow.

I do think your plant is nearing end of its time, so don’t be super critical about making leaves look beautiful.

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#9

Thanks! “looking beautiful” LOL! So, “functional outcomes” over “aesthetics” becomes the goal…that does help! Actually, the pH on the runoff was about 5.8. Does that have a bearing? Also, I have more “learning” to do; “base nutrients” are that which is already in the soil; “concentration” of base nutrients being indicated by ppm? Also, if pH is lower in runoff than recommended should pH be “higher” and within range of feeding?

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#10

Sorry, I meant N “toxicity.”

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#11

Going in at 6.5 and coming out at 5.8 means your root zone ph is trending down. Depending on how long it’s been that way, could cause issues. And yes, pretty typical when you see this to just raise ph of solution a little and then pour a little extra through to try and bring back up. Amending your soil with a little lime can help buffer ph too.

By base nutrients i just mean your typical nutrients. Could be placed in your soil if that is how you plan to feed your plants. Or could be applied in multiple part from bottles.

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#12

Your yellowing leaves is something that I experienced years ago and decided was unacceptable. I prefer to support the plant through the entire grow with a green canopy and most nutrient lines discontinue (or severely cut back) N which causes yellowing issues in later flower. It’s really too late for you to see major changes to the plant at this stage as all yellowing leaves will not improve. You have to look to new growth for signs of improvement and in late flower you won’t get much new growth.

I would prefer to see this runoff number around 1,000 ppm in soil at this point so your media is pretty depleted. You should get a decent harvest though. Plant does not look bad for your first grow.

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#13

Great feedback, thank you!

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#14

Thank you!

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