Yellow spots & dark leaf fringe. Over-doing the nutes?

1. Indoor or outdoor? - size of grow? 4x4 tent with 6 plants in 5 gallon fabric pots
2. Otigin of seeds? ILGM WW
3. Regular, feminized, or autoflower? Auto
4. Origin of water. PH, EC/TDS of source water? RO water
5. PH and TDS/EC of if mixed solution? PH to 6.1 when in cups w Coco-Loco soil. Changed to 5.9 when repotted in coco / perlite (70/30)
6. Grow method? Soil, Soil-less, Coco, Hydro, Aquaponics. Please explain. Coco Loco in Solo cups for 1st two weeks. Repotted in coco/perlite 3 days ago.
7. Nutrients or fertilizer system used. RO w/ Cal-Mag in cups. Full strength Jack’s 321 once I switched to coco / perlite.
8. What typr of lighting are you using? LED, HID (MH, CMH, HPS), or Fluorescents? LED. Spider-Farmer SF4000 30" above canopy and set to 50%. Measuring about 400 umols at the canopy using Photone and Iphone 7.
9. What are the temps in your growspce? 18 hours on averaging 75 F (AC Infinity controller set to max 77 F)
10. What is the RH = relative humidity in your growspace? Day / Night? Stays at approximately 65% (controller set to 65%)
11. AC, Humidifier, De-humidifier? Dehumdifier (self draining) in bedroom set to 40% and maintaining that.
12. Do you have a Ventilation system? Size? 4", 6"? 6" AC Infinity S6 fan with Controller 67.
13. Co2 Yes / No? No
14. How long have you been growing? 3 weeks / first grow
15. What budget have you set in order to grow successfully? Passed that point long ago.

Plants are 18 days above ground. The first two weeks was in Coco Loco Solo cups, which is coco with numerous amendments. During the Solo cup days they were watered every 3-4 days with RO and Cal-Mag.
At day 15 they were transplanted (Coco Loco intact) into a coco / perlite mix in 5 gallon buckets. Since transfer they’ve been getting daily RO with Jack’s 321 at full strength with 50% to 100% run-off (still trying to dial that one in). PH of mix is 5.9.

Overnight, one of the plants developed yellow blotches on two leaves. This is the same plant that had some sort of nute burn in week 1-ish, probably from a hot spot in the media. I’m seeing much smaller spots on other plants. Very faint and very small. More like light freckles. The fringe of many leaves is fairly dark green on all the plants, with some curling down slightly. Much more noticeable on the lower leaves than the upper.

My diagnosis, based on my vast experience (3 weeks) and a handy pictorial diagnosis chart, is that I have over-dosed on the nutrients. Since the roots are all still mostly in the Coco Loco and CL has all those amendments the Jacks I fed with were too much.

The questions now are “am I right?” and “What now?”. My thought is to flush with a couple gallons of RO & Cal-Mag, then give it a couple days before starting back with Jack’s at half strength? Thoughts?

Leaves that come in contact with soil/medium, always get damaged, and die off. I think this is the case here. I would resume full dose feedings of Jacks. Top growth looks good.


Groovy. Just overthinking it and hearing footsteps, I guess. Thanks for the quick response.

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