Theses plants are 4 weeks old. I only used pro mix and no fertilizer to date. My ph level is kepted a 6.5. Being grown under 4 300 watt led lights. This is my fourth grow and every grow has ended up this way.
I’m thinking if your pH really is 6.5 then you probably need to be feeding them something by this time. The leaves do appear to have symptoms that would point to numerous nutrient deficiencies – nitrogen, potassium, magnesium, sulfur and iron could all be causing similar discoloring that is seen in the picture, but it is hard to say with the LED’s not showing true leaf colors. It could be mostly one nutrient is deficient or it could very well be a combination of all of them. Feeding them a properly balanced nutrient system at this time would probably be a good idea.
How are you testing your pH? Are you testing the water that is given to the plants? Also are testing some run-off after watering to get an idea of what the pH is at the roots?
I did test the run off water it tested at 6.6 ph. I used a digital ph meter which I calibrate monthly. I started fertilizer today using botanical pro blend. I wait two or three days to see what happens. Thank you very much for your email and thoughts I appreciate it very much. You guys are awesome.
In the future you can add nutrients a little sooner. You can add nutrients after a few sets of true leaves and accompanying alternating nodes have developed. Not all discoloring may go away, but new growth should look vibrant and evenly green.