Hey Marmarb, I start my feedings @ about that point 3 to 4 weeks. I simply follow the directions on the bottles but when I start, I start at 1/4th of what it says then i build up. Your plants will take what ever you give to it just remember to introduce it slowly. so if it says like 2tsp per gallon of water id do 1/2 tsp per water then 1 tsp the next time then 2 tsp the next time when feeding food to them.Ive been growing my blue hash and diesel ryder in fox farm soil they are about 3 weeks old there is any yellowing of the leaves or anything just wondering when should i start adding these nutes also how much of the flora mirco i have the entire set thanks alot