Please allow me to rephrase your question:

I live in (your town name here), Florida. My lawn is St Augustine and there is one part, in full sun, which has not ever done well in 4 years.

I'm trying to put a more positive spin on the question, because St Augustine is the dominant turfgrass for the area. Healthy St Aug should choke out everything.

I need to know a few more things.

How often do you water and for how long?

How high/low do you mow?

When were the last two times you fertilized and what did you use?

Have you ever used herbicide, fungicide, or insecticide on the lawn? If so, what did you use?

Is there any reason to think that the soil was damaged during construction? Could they have buried construction rubble there? Were there trees removed from the area? Any wood buried there?

Thanks for the response and re-phrasing it.

We water twice a week for about 15 minutes.

When I mow I set the blade high. So I don't mow the grass down real low.

We had a landscaping company that would treat our lawn, and they used some herbicides and I recently (two weeks ago) treated with Turfbuilder S. I am trying to take over maintenance of the lawn myself out of interest.

I think the soil is in good shape... I don't think there is buried rubble. The lots was cleared, so, yes, trees, etc., were removed, but they built up the lot from there and did put dirt on top, and that doesn't seem to be a problem.

Mowing high is right! Congrats there.

Chances are the watering needs a tune up. Get some empty cat food or tuna cans and place them around the yard. Turn on the sprinkler and time how long it takes to fill the cans. That is the time you should be watering. I would be surprised if 15 minutes is long enough. This time of year you should be watering more like once per week in your part of the country - assuming you have temps in the 90s or high 80s. What this watering regimen will do is develop deep roots which can withstand the heat and dryness of summer. I'm hoping just correcting the water will do it for you.

You fertilized a little early. In your case it might not make much difference, but with a normal lawn in good health, you should wait until all the fast growth of spring is finished to fertilize for the first time. I realize the weekend TV is full of Scott's commercials telling you something different, but they're selling fertilizer.

Thanks! I'll try that with the cans.

As for the fertilizer, is there one you (or anyone else) really recommend? Like I said, I used the Scott's Turfbuilder S. Is there anything else that's better/more effective, etc., that is available over the counter. (in other words, not something I'd have to have a chemistry degree to mix and use).

Since you asked...I like alfalfa pellets (rabbit chow) from the local feed store. Now before you think I read the wrong question, here is a picture taken by Gardenweb member, mrmumbles, back in 2011. He fertilized his zoysia with alfalfa pellets in mid May and took the picture in Mid June.

{{gwi:79339}}

It works! The application rate is 20 pounds per 1,000 square feet. You can apply it once per year, once per month, once per week, or whenever. How much do you want to spend on this hobby? 50-pounds should cost about $13.00.