Question
QUESTION: I currently live in Florida and was reading a past article regarding Mn and Mg for Florida soils. I am dealing with a lot of our clients lawns having very high calcium ratios and am curios on your thought about what makes up the best fertilizer for St. Augustine grass during this month. what is the best approach to have a thick green lawn? Thanks for your time!

ANSWER: First, check your pH.  If it's not 6.5, adjust your pH. St. Augustine can become chlorotic in alkaline soil.  Use a good quality turf fertilizer with micro nutrients and especially iron.  In sandy soils, apply 1 lb. of nitrogen per 1000 sq. ft. every thirty days.  In clay soils, cut the rate in half. It needs very little phosphorous and about 1/2 as much potassium as nitrogen, so I'd like to have a fertilizer that is close to a 2-0-1 ratio (24-0-12, etc.).
Mowing height and frequency is critical for good health.  In full sun and 2" or less in height, mow every 5 days.  At 2.5" mow every 7-10 days. In the shade, mow at 3" every 10-14 days.
Don't exceed this rate for nitrogen. Over fertilizing makes the grass much more susceptible to insect and disease damage and thatch buildup.  Jim

---------- FOLLOW-UP ----------

QUESTION: Thanks. What are your thoughts regarding the fertilizer and the make of the fertilizer?? Meaning the sulfur and chlorine in it? Do you think there is a better composition?

Answer
A good quality turf fertilizer shouldn't have any chlorine in it.  It should have some sulfur or sulfates in it.  I don't care whose name is on the label.  Snoop around your local golf course or ask the local golf course distributor what the courses are using in the area.  You can't go wrong that way.  The rate and frequency is different, but the fertilizer makeup for bermuda and St. Augustine are very similar. If golfers are happy, homeowners will be happy with the results.  Jim