Well ive had purple stems on my seedlings in the past that i believe have caused very slow growth and stunting problems that im trying to fix.i started a new group thats a week and 2 days old now that look very good and am catching the slightest purple tint on the stems now. I believe this is caused by a nitrogen or phosphorus deficiency.So ive given them a half strength of grow big. Right now their in straight roots organic soil in my deep cell greenhouse and i am going to transplant into 1 gal pots in a few days. Does anyone else get this purple tint on the leaf stems in the seedling stage??? it seems like they get it as soon as the 3rd leaf set is forming. By the look of the pics can you notice a nitrogen deficiency starting to show with the new leaf sets yellowing a bit???