Penny- If you really want to know whats going on with the yard, you need to take a couple soil samples to your nearest Ag. center for some tests. It only costs a couple bucks.
No use putting a lot of time and money in grass if there's something wrong with the soil. The reason I say this is because you mentioned that the yard is mainly sand, which means even the weeds aren't growing very well. Something not right there.
Another question--is the yard mostly sunny or shady? St. Augustine for the most part likes full sun, although there are strains of it that are adaptable to shade, like palmetto or bitter-blue. There's even a new one called Captiva that grows in full shade.
If the soil turns out to be o.k. and re-sodding the whole yard is out of the question, start with pieces of sod(1x2 ft.) that you can lay down in a checker-board pattern and fill in the empty spaces with top soil--which is pretty cheap also. You must keep it moist for the first week or so until it takes root. I wouldn't worry about laying sod now because its still too cold and most grass is dormant until the soil reaches and stays at least 65 degrees day and night.
I have found that there are certain weed killers made specifically for St. Augustine grasses, and if you use just any old weed killer for "southern lawns" it will do more harm than good. I use a product called" Atrazine"--brand name" Image" that you can buy pre-mixed that works very well. You spray it on and then a week later you do it again. This is a good time of year to do that before the weeds really take off. Now if you get rid of the weeds and just let the soil stay empty of vegetation your weeds will come back.
Also the U of Fla has found that a fertilizer of something like 10-0-10 or 16-4-8 with 4% magnesium which is more like something you'd use for palms, works really well for St. Augustine about 4 times a year--smaller(lighter) feedings instead of a couple times a year (spring/fall) of heavy feedings. This stuff is not cheap. The only company I've found that makes it is Lesco-a pro landscape business that deals mainly with big-time horticulture guys.
I buy a good 16-4-8 at Lowe's and add my own Mg.-about a pound per 25 pound bag of fert. Get yourself a good pull-behind spreader and hook it to the back of your new riding mower--makes the job real easy.
All grasses have their own special problems, with ST. Augustine its chinch bugs or a brown spot fungus and dollar weed. Pesticide for chinch bug is pretty easy to use and easy to prevent them, the fungus and dollarweed (an aquatic weed) comes about from too much water. Copper fungicides on the hose-end sprayer work good as well, but you have to keep after it until its gone. Just spraying it when you happen to remember will not do! It takes a regimented schedule to have a nice yard. My garden calender
is full of stuff to remember and do for the whole year!!
Hope I didn't scare you into concreteing the whole yard and painting it green!!!!
I know what you mean.
