Seedlings blotching marks

Had my seedlings growing and noticed the tips of the new growth was going purple/pink on all of my strains. It's mid winter here so I put a heat mat in and that got rid of the purpling however now I have this blotching on the leaves. Is this over watering/under watering, frost, nutrient deficiencies or something else entirely?

Its likely nutrient deficiencies from environmental factors. The heat helped with moderate phos deficiencies but the lack of airflow and or transpiration in your space could be contributing to others.
With the tips a better color green there could be need to uppot or feed more as it could be now a deficiency in the soil or feeds now that the root zone is at a better temperature.

Red Hard Head said:

Its likely nutrient deficiencies from environmental factors. The heat helped with moderate phos deficiencies but the lack of airflow and or transpiration in your space could be contributing to others.
With the tips a better color green there could be need to uppot or feed more as it could be now a deficiency in the soil or feeds now that the root zone is at a better temperature.

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They were just in straight seed raising mix so that makes sense. My friends that live in the same town are having the same issue with their seedlings and they are growing in organics so I assumed it was from the cold snap we have been having as of late.

Thanks for the quick reply!

I've got a box fan outside the small tent blowing through one of the liftable pouches that I put in 3-4 days ago so hopefully that helps with the airflow. Need to get some smaller clip on fans that'll fit inside my 2x2 just running on a budget since I spent $$ on some new beans

Gave 3 of the dry plants a feeding of 8-3-6 liquid blood and bone meal. Usually takes 2-4 days to see results so hopefully that helps