I live in Northeast Florida, and have St. Augustine grass. I usually fertilize in late March, and around mid-September.
When I fertilized in March, I could see the grass turn greener and start growing faster within about ten days. The difference was very obvious.
When I fertilized again three weeks ago, I ran out of time, and only got to half my yard. Thus, I can easily compare where I have fertilized and where I haven't.
I can't see ANY difference whatsoever as to where I put down new fertilizer and where I haven't. The area fertilized has not greened a bit, and the grass blade growth rate is no different than the areas where I did not fertilize. In short, this fertilizer has had NO effect on my lawn. After three weeks, I should see obvious greening, and obvious growth enhancement, but I don't.
I used Scott's Turfbuilder. I don't recall the exact formula, but it was something like 24-8-16. I spread it at the recommended rate, watered it in, and the lawn has had an inch of rain per week during these three weeks. Our daytime temps are still in the high 80's to low 90's, so the grass is still growing.
I don't see much point in now fertilizing the other half, if this application has shown no reponse.
Does anyone have any idea of why I am experiencing this with my lawn ? By the way, the lawn looks pretty decent, considering the fact that the prior feeding was back in March. It is relatively green, and growing normally, although at a slowed rate. I don't seem to have any decline, insects, or fungus. I just don't know why it doesn't seem to respond to fertilizer.
I will appreciate any ideas or comments.