St Aug should be weed free under the following conditions.

1. Soil is not kept continually moist. You should water no more often than monthly this time of year and no more often than weekly during the hottest part of summer. This means you will be watering for hours (and hours???) at a time when you do water. With my water pressure I water for 5 hours per zone in the hottest, driest part of summer. That puts 5/8 inch of water on with my water pressure and sprinkler setting. When the soil is kept moist all the time, you are setting up perfect conditions for sprouting seeds - weed seeds. By letting the surface of the soil dry out between watering, the weed seeds cannot sprout.

2. Grass is always mowed at the highest setting. There is never any reason to mow St Aug lower than the highest setting. Tall grass grows deep roots that can penetrate to get the water you put down in 1 above. Tall grass shades any of the weed seedlings that might have sprouted during a prolonged rain storm.

3. Fertilize regularly. I am in the same zone and start on Washington's birthday. Next is Memorial Day, 4th of July, Labor Day, and Thanksgiving. Don't skimp. It really helps to keep the lawn dense and weed free.

St Augustine should spread up to 10 feet per year. One issue with this plan is this: St Aug likes moist soil to spread. The best time of year to get it spreading is now because there are much fewer weeds sprouting this time of year. So for now you can pull your weeds and water every week or when the soil surface feels dry, but do let it dry some. Watering ever day for 10 minutes is not a good plan.