Minor discoloration on seedlings (nitrogen toxicity?)

Curling leaves and discoloration? Yep, nitrogen toxicity. Just hit it with pH'ed water(6.4) for a week or so and it should recover fine. I hope this helps. Good luck.

Young ones struggle with N+. Better not to feed them until they re toddlers.

This looks like overwatering to me and a bit of a feeding issue but nothing major. Try not to saturate the medium to much as the roots are having issues getting oxygen to them and that's why the leaves are growing in weird, at least that how it presents for me in the past with similar issues. Regarding ProMix, its a fine medium to use if you like peat based, some of them are fortified with slow release nutrients and that can be a bit much for some autos. and it can mess up your feeding chats as they spike the EC values of the medium and its unknown. Best Of Luck! ***disclaimer, multiple people are answering all questions as there is a contest called GOTM, when a user is selected as the answer they get a point. Please see the contest page for information regarding the details: growdiaries.com/giveaways/GotM-August-2022 Please note, when you reply to anything on the questions part of Growdiaries website, no one will be notified of this. Not even if you use a "@" tag in their name. Best to reach out to them in DM using your inbox, it can be found in the bottom right hand corner of the site. It's the small paper airplane button, it will be highlighted green if you have new messages***

High Captain, This is a Nitrogen toxicity, the result of the plant getting too much Nitrogen (usually from too high levels of nutrients overall, or by using a Vegetative nutrient in the flowering stage). It causes dark green leaves and curled tips (“the claw”). One of the main symptoms of a Nitrogen toxicity is curled tips (“the claw”). And that claw is pretty obvious when I look at your pictures. You need to flush the soil and after flushing give less Nitrogen nutrients. You can do this flushing by slowly pour water pH 6.2 onto the top of the soil, allowing it to drain freely from the bottom of the pot. Pour slowly, so the water doesn't overflow from the top of the pot. Use approximately four times the pot's volume in water to flush the soil. For example, use 1 gallon of water for a 1 quart pot. After the flushing you need to let the soil (almost) dry out completely. And from here you continue your grow as you did before but now with less Nitrogen. Happy Growing! 😋

Hmmm that’s an unusual symptom. I scoped the diary and you’re using promix.. now most promix is void of nutrients essentially.. Unless you got an actual soil that is amended from them.. which I believe they do have but it’s not common. Anyhow.. I wouldn’t worry too much at this point. If it is the promix HP or similar, the ones without nutes - you’re in a “soilless “ medium and will be needing to supply the plant it’s nutrients in the water. I use GH, the trio not the flora nova but that’s good stuff from what I’ve heard from other growers. Make sure your pH of water/feed is on point cuz that will cause issues quickly if it’s not..