Hi guys , i need some help , this is my second grow , my seedling is 3 weeks old , i started step by step making them get used to oudoors, so 2 hours shade first day ,and then 3 hours , then 4 , then 2 hours shade 1 hour sun and so on , but i'm realizing as my plant is giving new leaves the old ones are turning yellowish and then drying becoming crispy and falling off, for sure overwatering is not my problem , what else might be the cause?