HELP! Older leaves curling under and forming patches

Someone Please HELP!! My babies are about a month and a half old. About a foot tall, under flourescents. I use distilled water. Planted in Miracle Grow Organic Potting Soil. I have been using the Miracle grow organic fertilizer that only has Nitrogen in it. I have been mixing into the top soil a tablespoon the last 4 times I have watered. Temp is around 79 degrees F and humidity is around 26 percent. Lights running 24hrs.

The older leaves have been curling under and twisting a bit on the edges of the leaf and the tips of the leaf. There are also dark patches forming on the older leaves as well. Stems have turned purple. One of the plants all the leaves are curling.

If anyone has any idea whats wrong please let me know. I have posted pics. Thanks

that only has Nitrogen in it.

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if you are just feeding nitrogen they will not be happy. you need a good n-p-k, like 30-15-15 for veg. even though N is key, the plant still needs p & k in veg.. same way in flower you need some N but mainly P & K. i would be lying if i said i knew what was wrong for sure though. they look like they are stretching a bit too (doubt anything to do with the yellowing/spotting).. normally the leafs should start an inch or 2 above the soil(some people even bury the first set of leaves). yours look to be about 6" above soil or more before your first set of leafs show.

Thanks for the quick reply. I definitely agree with you. Do you think I should add some more soil from the bag to the top of the pots? Just for now until my Humboldt Nutes come in, in a few days??