Scotts Liquid Turf Builder with Plus 2 Weed Control is not labeled for St Augustine turfgrass. Please provide the type of St. Augustine turfgrass species that you have along with the weeds you wish to eradicate or prevent for a product recommendation. You can also contact your cooperative extension office if you are unsure of the weed or turf species.
Per the Product Label for the Scotts Liquid Turf Builder with Plus 2 Weed Control: A quart size bottle will cover about 6k sq/ft of a warm season lawn and about 4k sq/ft of a cool season lawn. We would not be able to tell you how long it will take for that bottle to empty as that is dependent on how fast you walk over your area and the output and pressure of your water hose.
Scotts Liquid Turf Builder with Plus 2 Weed Control should be hooked to a hose and will turn on and off. There is not a way to adjust the spray pattern.
You do not have to use the entire bottle of Scotts Liquid Turf Builder with Plus 2 Weed Control at one time. You should know the size of the area that you need to treat, and then start at one side and apply evenly to the area without overlap. Be sure you do not spray plants to the point of runoff. On cool season grasses, the quart bottle should cover 4,000 sq ft total.
We would recommend contacting the manufacturer of the Scotts Liquid Turf Builder with Plus 2 Weed Control directly as they make the units and would better be able to troubleshoot the device with you to get it working for your needs. You can reach Scotts at 888-270-3714.
