it's not greening up as fast as i expected. i put 1/2 gallon of iron on my 1/4 acre lot. i put it down 3 days ago. i let it sit for about 1/2 a day then i watered it in. what should i expect?? should i just be patient???? wait for some rain???? i am looking to get the dark green effect, i already have a pretty healthy lawn. is there anything that i am missing???