First you need to decide what kind of grass you want to have. I can decide that for you from 2,000 miles away if you like. Here it is. You want St Augustine. You probably want the variety called Floratam developed by the University of Florda and Texas A&M University (hence Floratam). The only way to grow new St Augustine grass is by sodding it. Since you are basically starting over, I would hire a landscaper with a tractor and a box blade (NOT a skid steer or a bobcat) to come in and scrape the surface of the entire yard. This will even out all the bumps and fill the holes to provide a perfectly draining surface ready for sodding. Then have the sod delivered. Gather all your friends so the sod can go down all at once on the day it is delivered (PIZZA party). Then roll the sod down with a rented, water fillable, roller. Water it morning, noon, and night for 3 weeks to knit the roots from the sod to the underlying soil. Set your mower for the highest setting and mow when the grass is at least 4 inches high. Eventually all the grass will grow up to that height and it will look excellent. Never lower your mower for any reason.

St Aug needs 1 inch of water per week to stay alive. Ideally that inch will be applied on one day. The frequent watering is ONLY for establishing new roots. If it turns straw colored, it's dead. But if you have one living plant left in the yard, you can restore the entire lawn from that one strand of grass. It really takes weeks of full sun and no water to kill it off, so almost any care will keep the grass alive. But if you want it to look nice you need to water weekly and mow weekly. I fertilize with organic fertilizer 5 times per year on the federal holidays. If you use synthetic fertilizer you can skip the 4th of July app because it is really too hot.

If, after this type of renovation, you still have weeds, we can talk about it. I think they will almost all be gone, though.

I would not go with Floratam, only because you have one choice of herbicide and that herbicide is toxic as hell. Its ban in Europe.

Go to Lowes/HD and buy a dial sprayer, the kind that you put concentrate in the bottom and turn the dial to what dose you want.
Then Go to Tractor Supply. Buy concentrate of 2,4-D. Fill up your sprayer and apply at 1 1/2 oz per gallon. Wait about 4 weeks and you should have a weed free lawn.

If you have St Aug then the above will also kill this type of grass.

If you do want floratam, go to Lowes/HD and buy a few yards of it and place them though out your yard. It will spread to cover your entire yard in a season or two.

I have so few weeds that I don't use use herbicides, so I'm not sure what botanicalbill is talking about. bb, what is the one you can use on Floratam?

I do agree with the idea of just getting a few flats of St Augustine. It will send runners out 10 feet in all directions in one good season. Before you know it you have a dense turf.

... botanicalbill only made this more confusing

What is confusing is that this a 13 year old thread so not exactly demanding of more comments!! And the entire thread is confusing as there is no way to determine where the OP lives so what type of turf they may have (is St Augustine/floratam even appropriate in this mystery location?). Also what kid of weeds? Annual weeds? Perennial weeds? Treatments and products will differ.

It would have been better to have let this thread rest in peace :-))

That is very weird that I would have made such a comment without clues as to the writer's location. All I can think is there were other comments made by the writer in other topics that gave it away. Besides, living in Texas, I'm not 2,000 miles away from anyplace where St Augustine would be the only best option.