Hey, these are my seedlings which are a few weeks old and are under 4 27-watt CFLs. Planted in 50% Monrovia Organic potting soil, 30% perilite and 20% worm castings. In the last 4 or so days 3 out out my 5 girls have developed burning (1st pic) and yellowing (2nd and 3rd pics). I think it could be too high of a pH, but this is my first time growing and need help figuring out what I should do. I do have a digital pH meter which has given me everything from 6.7 to 7.3 in the same pot at the same time; I'm trying to find regular litmus paper which I much prefer but haven't had any luck yet. I'd greatly appreciate it!
I did add an 1/8th of a tbsp of lemon juice to the gallon of water I watered the plants with today, and took them outside for a good 6 hour so hours of real, solid sunlight. Hopefully I will see some improvement/no more damage.
That's an unusual condition for seedlings. The way the plant in the first pic is showing patches of necrosis in fairly random spots is common with Phosphorus deficiency, but such small plants don't usually exhibit such strong symptoms of P-def. The other two look more like a slight burning that may be from something other than nutrients. I would start by flushing the next time the soil dries and then feed them a 2/3 strength, high-P, pH'd, organic fertilizer tea when the soil dries out again. This can wash away high or low pH substances to create a better soil pH, as well as anything that's burning them. Bone Meal and high-P Guanos are some of the best sources of Phosphorus.