I'm doing an experiment with unmowed St Augustine. Originally I did not think the grass would get taller than 10 inches, but it is easily 36 inches in one spot under a tree. Here is a picture I took last year. The purpose of the experiment was to demonstrate the benefits that lou mentioned above. I stopped mowing in October of 2011. The location is George West, TX on the edge of the Texas desert. Temps are above 95 from mid May through mid October with humidity running 40-50% most of the time. Since then I have only watered the grass when and where it was calling out to me for water. At no time have I watered more frequently than once per week. There is one spot under a tree on the east side of the house where I have not watered at all since 10/2011. In fact that is where the dog picture was taken. At the time it was about 30 inches high right there. Also since then I have not fertilized and used no insecticide or herbicide. As you can see there is no weed pressure at all - and I am surrounded by fields of King Ranch bluestem. There are places in the yard with plenty of bluestem, bermuda, and other weeds, but those areas are not part of this experiment. So the point of mentioning this is that taller St Aug will resist all the problems you might have with anything else. I always suggest people weld their mower at the highest position to prevent your well-meaning brother in lawn from doing you a favor and scalping your lawn back down "to where it should be." Tall St Aug (4 inches, not 40) is very lush looking and will solve your problems. Another issue you should watch for is drought stress near the sidewalk. Sidewalks take up sunlight all day and remain warm much longer that the soil under the grass. The soil near the sidewalk will get warmer during the day and remain warm until the next day. This tends to drive off the moisture through evaporation near the sidewalk and dry out the grass. The solution is to water more deeply, not more often. Generally I agree that your only problem is the grass roots are not up to speed yet. Give it another month and take another picture to compare. You should see improvement. Set your mower high, water deeply and infrequently, and fertilize and you will have a lawn like your neighbor. I prefer organic fertilizer because I am lazy and don't like to measure, but you can use chemical and get good results, too.

The only way you can know about your sprinklers is to put out tuna or cat food cans and see how full they get as you water. It takes 8 hours to fill on my yard but only 20 minutes to fill on my neighbor's. Everyone has to do this if they want to know what it means to water 1 inch. There are low flow sprinkler heads. A friend in Phoenix has soil similar to what you described and solved his problem with shampoo (see below) and the low flow heads. These heads are gear driven and send out a small stream of water on a rotator. Of course he waters a lot longer but the same amount of water hits the soil. You definitely don't want runoff. That's just wasting the water. You can try applying 3 ounces per 1,000 square feet of any clear shampoo right before you water. I have used the generic baby shampoo from Wal-mart as well as Alberto Vo5. Both are pretty cheap solution to the water penetration issue. The soap will allow the water to penetrate deeper. Apply it once now, water normally next week, and repeat the shampoo in 2 weeks. Don't use dish soap. Shampoo is used for a reason. When you see runoff, turn off the sprinklers immediately and let the moisture soak in for 20 to 30 minutes. Then try to get the rest of the inch of water into the soil. Palmetto is semi-dwarf. 3 inches should be good. Yes, the grass will all come up to that height. That will really help with the bermuda control. St Augustine works by using its coarser blades to put more shade onto the bermuda grass until the bermuda is completely shaded out. One flaw in this plan is the Palmetto has finer blades (less shade) and it likes being shorter (like bermuda). I've had pretty good success taking my lawn back from bermuda, but I have common St Aug and Floratam. Tall grass getting more fungus? Not that I've noticed. I have a second yard at a house in George West. It is a large yard with Floratam ranging from 12 inches high up to 32 inches and no signs of fungus that I've noticed. Here is a picture. That grass is about 18 inches high.

Welcome to lawn care...and stop watering!! You are killing your lawn with kindness. I'll explain. Look carefully at this picture. See how the spot forms an oval right in the middle of the drainage swale? What you have is standing water right there that has contributed to a fungal disease. I'm going to make the wild assertion that all your dead grass is due to a fungal disease simply because you are watering wrong. St Augustine grass, especially in Houston and especially this time of year, only needs to be watered once every 10 days or so. You are watering more like you were establishing a new lawn. Now you need to back off. I would wean it by skipping days and increasing the time. To start with you should water about an inch every time you water. Measure how long it takes to fill a tuna can using your sprinkler system. Then water for that length of time when you water. Watch the grass for signs of wilting to get the timing for your watering. Sometimes you can go 14 days in the spring and fall. In the winter go to a monthly schedule even if the grass is dormant. When the summer heat cranks back up, you can go to every 7 days and maybe to a 5-day schedule if 7 isn't working. The big point is that you are watering shallow and often. You should be watering deep and infrequently. Frequent watering is also the reason for your weeds. Grass and weed seeds need frequent watering in order to sprout. By backing off on the watering you will cut off the supply of water at the very surface of the soil and virtually stop the new weeds. The reason your attempts to kill the weeds has not worked is you are using the wrong product. Weed n Feed comes up in the forums all the time. It just doesn't do what you expect it to do. The reason seems to do with timing of the product. Weeds die best when they are well fertilized. But by the time the fertilizer part of the WnF product kicks in, the herbicide is long gone. You will have much better results using a plain fertilizer at the recommended rate and then, spot spray individual weeds with something like Weed-B-Gone two weeks after the fertilizer. You will also save a lot of money and frustration. If you want to try that again but you're afraid of killing the grass with too much fertilizer, you can use organic fertilizer instead. The two types of fertilizer have absolutely no cross interactions that would cause you to worry. But in the case of organic, it takes 3 full weeks to see results, so wait 3 weeks instead of 2 before you use the WbG. The last thing with St Augustine is to keep it mowed at the mower's highest setting. There is never any reason to lower the mowing height of St Aug. One more last thing, whatever that weed is should die out from Weed-b-Gone. Be sure to use the Weed-b-Gone in the black bottle with the purple label. That is the only one safe for St Augustine. But do not spray and breath the spray or get it on your or pets. Keep the kids and pets away until it has dried. The less of that you can get away with using the better. Your lawn looks very good, by the way...except for the minor amount of dead stuff. We see some pretty crappy lawns in the forums. Hopefully yours will never become one of those.

Just writing to provide an update. I went ahead with the cardboard and mulch. First, I emptied all my compost and several bags of chicken manure onto the grass. Then, covered it with a roll of 4ft wide cardboard. I didn't mind paying $100 for cardboard because my costs will be reimbursed by the county offering the program. Then, with the help of my father in law's truck we found some free mulch at a nursery. We thought this was great, though I wasn't satisfied with the coverage. We spread it evenly, but it was pretty thin. It took a few more weeks but I found a tree company that sold "fine" mulch by the cubic yard. I ordered a delivery of 8 yards, with a yard of compost mixed in. This spread evenly and it is covered across the yard by about 4-6 inches of fine mulch/compost mix. Closeup of the fine mulch, bricks for scale. Here in Orange County it has been very hot this summer, approaching 100 degrees today. I've been watering it a couple times a week, and raking it over once a week. I've peeked underneath and the grass does not look happy. :) It's been covered for a solid month now in the heat of summer. I pick or spray the stragglers around the edges. I am wondering, should I add some source of nitrogen to the mulch to help it decompose faster? Any suggestion? I spread some fertilizer on top of it and wet it down, but that might be paltry for the requirements. I need to plant by the end of November to get the rebate.