Yellowing new growth!?

consider recent behaviour.. eliminate possiblity of lockout. looks like a S deficiency. S can easily be locked out by other things. growing out of it doesn't mean you are in the clear, but sometimes new growth can take a second to fill in. The fact you can notice slowdown in growth leads me to think it's deficiency or lockout. But, could be due to other environmental factors like the temperature you mention. So take it slowly.. check guarnateed analysis labels of your fertilizers and add up PPMs in total of each nutrient. compare to other mixes (i have one pictured every week in my diaries NPK, secondary and trace) main concernL P 50-60ppm K 180-200ppm even look into Ca, Mg... these 5 things can lock each other out. if one is too high it'll mess with something in this group (Ca Mg, S, P, K) now, if you are soil this translates as the ppm when you think the soil's starting nutrients are used up and you are providing what the plant needs... early on in soil you definitely do NOT want anything near these PPM.