That's great advice from Ric, but be patient. Turf has really slowed down here in TX, and will come to a halt in the next couple of weeks. If you're south of a line from Corpus Christi to Laredo, you may see a response, but otherwise, it's real close to "bed time" for lawns in TX.
St. Aug can hang on to it's green color (but not the vibrant green) during the winter, but with the cool nights and shorter days growth pretty much stops after Thanksgiving.
In the winter, we're a lot drier than Florida. The very dry air heats and cools quickly. After Thanksgiving, we routinely get hard freezes at night here in TX, with wild temperature swings during the days. It's not uncommon for us to get down into the 20's at night and warm into the 70's during the day.
But a good dose of sewage sludge now will pay dividends in the spring. Hit it with a 1-0-1 ratio fert at green-up.