End of week 3 of flower. Stretch has slowed down and plants seem to be close to their final height. Tallest cola is 42 inches and 16 inches from the light. No signs of light stress. Very minor tip burn on fan leaves which I attribute to increased transpiration and water requirements. On day 18 I noticed the largest plant had drank almost all the moisture from the 4 pm fertigation by 6:00 pm and so I've adjusted the feeding frequency and duration.
Lights on 9:00 am
First fertigation @ 9:30 for 30 seconds
2nd fertigation @ 11:00 for 20 seconds
3rd fertigation @ 12:30 for 20 seconds
4th fertigation @ 2:00 for 20 seconds
5th fertigation @ 3:30 for 20 seconds
6th fertigation @ 5:00 for 20 seconds
7th fertigation @ 6:30 for 20 seconds
8th fertigation @ 8:00 for 30 seconds
Lights off at 9:00 pm
Lollipopped the lower half of the plants. No further defoliation planned for the remainder of the cycle.
Light is now@ 78%. Plan is to increase by 1% each day for the next 3 weeks ramping up to 100% by the end of week 6 of flower. Will increase Co2 accordingly up to 1100 ppm.
I'm not sure if this is nutrient burn or a cal/mag issue (deficiency or lockout), or something else. Anybody know what is likely to be causing this, and how to treat it?
I don't think it's a cal mag problem. It could be due to using up the potassium. I would be tempted to leave your nutes as is but increase the bloom slightly and see how that goes.