Mother Nature surely knows how to show us who is in charge.
The good news is that the lowest temperature we hit two weeks ago during the cold snap was 42 degrees F, 1 degree above the 41 that would outright kill seedling cotton. The not-so-good news — for me, anyway — is she blew my recommendation of waiting two weeks after hitting and holding 4-inch soil-depth temperature of 65 before applying lawn fertilizers right out of the water.
On April 19, the 4-inch temperature dropped to 62. That dip reset the clock for fertilizer, which made this past Monday the starting date for applying lawn fertilizers in Bryan County. I was two weeks early with the green flag. Waiting until May before starting lawn fertilizers still is good for Bryan County, even though the new U.S. Department of Agriculture plant-hardiness zone map has moved Zone 9a north from the St. Johns River to the Medway Sound.
If you have St. Augustine turf, now is the right time to put down that first application of slow-release nitrogen fertilizer.
If you are a devotee of weed and feed, go ahead and use it on your St. Augustine turf.
Weed and feed is designed for growing season use. Weed-and-feed formulations generally are formulated so that the proper rate of application will deliver an effective dose of the herbicide and 1 pound of nitrogen per 1,000 square feet of lawn.
I recommend that you follow the label directions on spreader settings. Stray very much below, and you will put on less nitrogen but also reduce the herbicide to a sub-lethal level for the weeds.
What doesn’t kill them just makes them stronger. Applying too high of a rate could burn your lawn with nitrogen and/or with the herbicide. Messing with the application rates on a weed and feed can create a new set of problems while not fixing the old ones.  
Centipede is a different story. Where St. Augustine likes four 1-pound applications of nitrogen per year, centipede does best with just one.  
That means that one weed-and-feed application hits the weeds and also puts all the fertilizer for the whole year down at one time.
Breaking the 1-pound nitrogen application into two half-pound applications, one in May and another in July, gives a more sustained growth rate and more even color. Doing that with a weed and feed just wastes the herbicide.
I prefer using fertilizer alone at the right time to do the job of fertilizer and the right herbicide alone at the right time to deal with the weeds, especially on centipede. If you are using a liquid herbicide, I recommend using tracking dye in the finish spray mix so you can see where you have sprayed and any weeds you might have missed. It usually is a food-grade blue dye that fades out after a couple days.
I am a big fan of slow-release nitrogen for lawns on our warm and porous coastal sands.
Yes, slow-release costs more per pound, but they are so much better at delivering the right amount of nitrogen over a long period of time that they easily are the best bang for the buck. Put out fast-release nitrogen and a good inch of rain can wash it all away — right into the marsh.
A slow-release only emits a little nitrogen at a time. A heavy rain only moves a small amount of nitrogen, and tomorrow the correct amount of nitrogen still will be there for the lawn. It is one time that the right thing to do is the right thing for everybody.
What is economical also is environmentally sound and convenient, all at once. Save the fast release for the garden. Those tomatoes will need a good dose of nitrogen in a hurry when they start to “make.”
Use the right tool for the job.

Gardner lives in Keller and is the UGA extension agent for Glynn County, serving South Bryan.