Yellow leaves curling under and Dark Green splotches,

Plants are about 10 days old. Growing under 28 watt CFLs in soil in 80 degrees.

About 2 days ago, I noticed one of the tips of the leaves had turned yellow. In the past 2 days, two of my plants (one of them one of the biggest) have had their primary leaves turn yellow around the edges. The leaves are now curling under, and have dark green splotches in parts. We keep them on a fiarly regular watering schedule (i.e. water when the pot is light and the water meter reads dry).

I have a PH meter, but it is a analog meter that isn't too accurate at times. The only fertilizer I used was a one time small does of Peter's (12 - 4 - 8.)

The lights are a good few inches away from the plant, and I am sure underwatering is not the problem. Did I burn the plants perhaps with that one use of the fertilizer, or is it something else? Of the 5 plants, 2 of them have been affected, with one more showing signs of yellow. What do I do?

Bump. Also update.

The yellowing continues to spread on the plants pictured, but I recently got a ph tester for my water, so I have been watering with the correct PH. The leaves on of the plants no longer curl under, but they are still yellowing. I have also noticed that the stalk is tinged purple. Any idea what this is? I am being told it is either phosphorus or potassium.

purple is normal the yellow looks like nute burn dont add nutes till the soil is used up about 30 days

there stretching

Yeah that one in there is stretched badly. And I should note that the only ones with purple stalks are the ones with yellow leaves.

JD886 said:

Yeah that one in there is stretched badly. And I should note that the only ones with purple stalks are the ones with yellow leaves.

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Purple stems are common but I would look into a Sulfur problem. Sulfur Def. Causes downward curling with yellow tips and dark green spotting. Sulfur def. Also can cause your stems to turn purple. Good luck.