Leaf tips discoloration

[SouthsideTone]

18 is not so close to cause light stress problems, but FYI I run a single 300 watt LED above each plant and I start my seedlings at 30 inches and let them grow up to within 24 inches, then leave it at 24 until the stretch is over, then I lower to 18 until harvest. I sometimes had trouble getting my girls to stretch good when I ran my lights closer.

Thx bro I was wondering how close my lights should b at this stage


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[KonopCh]

Southside-- let me confirm, you have 30% vermiculite in the coco, or do you mean perlite? Vermiculite will be problematic in coco, totally unnecessary,.. have you done some research about coco growing? there are many do's and don't's with it, because of it's unusual properties as a growing medium,... it can't be treated like a true soil at all, it's a bit more like hydro' in some ways,...
So, you say the burning started before you fed the first time? What are you using, dosage and frequency? Did you happen to pre-fert' the coco beforehand? What brand of coco is it? Some brands are not very good, often poorly washed and not aged enough to leach out the excess Na and K,...
...to my eye, this isn't a nute burn thing, the newest growth isn't showing any signs, no tip burn, distortions, and with lowers wasting out like that, there almost certainly would be,...it looks like a defc., P if anything,... get me the info and we'll dial it in more!

Why can be vermiculite problem in coco? Isn't better than perlite, because it holds 20% more water/air?