Yellow bottom leaves

I am growing two plants in my window. My problem is the two bottom leaves are starting to yellow. The plants are about 5 and 3 inches high. I just started fertilizing today to see if it would stop. I am using potting soil with rocks in the bottom. I have been testing the soil with my finger, when it starts to feel dry I give them about 6 oz of water each. Anything to help would be appreciated.

they need nitrogen, they should respond to the fertalizer nicely... if not get something with a higher N rating

water once every 3 days with 1/4 nitrogen nutes, then flush with pure H2O

if the bottom leaves u are referring to are the first set of leaves that u see when the plant sprouts then dont worry about it as those will fall off anyways....how old are the plants??