OK, now you can start putting fertilizer on your lawn.
Our soil temperatures at a 4-inch depth crept up past 65 degrees Fahrenheit on April 7 or 8 and have stayed up since then. This past Sunday gave us two full weeks for enzyme systems to get working, so your lawn should be up and ready for breakfast.
Congratulations to you if you have resisted the encouragement from the Scot to “Feed your lawn, feed it!” Last week would have been too early. Now you can start. Or you can wait a couple weeks until you get around to it. The window of opportunity for the first fertilizer application to centipede or St. Augustine lawns is open until the end of May.
Centipede lawns should be getting half a pound of nitrogen in this first application. For example, if one is applying a 15-0-15 fertilizer, only 3 1/3 pounds of fertilizer is needed for each 1,000 square feet of lawn. That is not much fertilizer. That is why we like centipede as a lawn grass; it has a very low nitrogen requirement.
Folks see how little fertilizer we recommend on centipede and just cannot believe that that small amount is enough. So they double or triple the amount. The grass greens up and looks grand for the first year, gets spotty the second year (so they push even more nitrogen to it) and then the third year it does not come out.
As a result, there is widespread belief that centipede lawns only last a few years. They do last only a few years if they are improperly maintained, but with proper care there is no reason why a centipede lawn should not outlive its owner.
After May, centipede lawns usually see their next (and last) fertilizer application for the year in July with another half-pound of nitrogen for each 1,000 square feet. One 40-pound bag of 15-0-15 fertilizer is enough to meet the fertilizer needs of a 6,000-square-foot centipede lawn for a year.
Now shift gears for a St. Augustine lawn. St. Augustine would like 1 pound of nitrogen per 1,000 square feet in May, again in June, a third application in August and a final pound in September. That is a total of 4 pounds of nitrogen per 1,000 square feet of lawn per year. That 40-pound bag of 15-0-15 fertilizer that fed 6,000 square feet of centipede for a year will be enough only for 1,500 square feet of St. Augustine for the year. St. Augustine turf demands four times as much nitrogen as centipede.
Some of you have weed-and-feed waiting to go out. It is still not time for that. St. Augustine owners can put out the weed and feed as one of the fertilizer treatments for June or July. Centipede-lawn owners who simply must put out a weed-and-feed should hold off on applying nitrogen until July and use the weed-and-feed as a one-shot nitrogen fertilizer for the year. If potassium is low on your centipede lawn, you can put out straight potash in May — but no nitrogen, please.
The weed-and-feed is mixed so a proper amount of herbicide is applied when the fertilizer is applied at a rate of 1 pound of nitrogen per 1,000 square feet. You cannot mess with the rate on the bag. Putting out half a pound of nitrogen will also put out half as much herbicide, so you might worry the weeds but you won’t kill them. If pesticides are mixed in with fertilizer, the pesticide rate rules, since the pesticide is even more expensive than the nitrogen. Now go forth and prosper.
Now, back to background. Time to define some terms. Clean means free of foreign matter. Sterile means devoid of life forms. Pathogen-free means absence of organisms that can cause disease. Natural means it occurs in the environment without human manipulation. Organic can mean so many different things to so many people that just listing the definitions would take a whole column.
Now, organic means so many different things that it means almost nothing. When I was in college, we needed manure that was free of weed seeds and pathogens to put in the growing beds of the research greenhouses. We put big trays of manure in the autoclave and cooked it with live steam. When it came out, it was sterile. It was devoid of life – right up until the time it cooled off enough for the bacteria and fungi in the air to settle on it and start colonizing this rich growing medium. Our manure was sterile — devoid of life, but by its very nature it was never clean and could never be clean, and yes, it did stink. It was natural and it was organic, too.
A shovel could be cleaned with a stream of water and a brush to remove foreign matter, but it was not sterile. If you needed the shovel to be pathogen-free we sterilized it. First, we cleaned it and then immersed it in a 10-percent solution of chlorine bleach for 10 minutes and then let it air-dry. This ensured we did not move pathogens around the research farm by accident. But when we picked up the shovel to use it again the next day, it was pathogen-free but it was no longer sterile. Fungi and bacteria had settled on it since it dried, so it had viable life forms on it.
Natural is neither good nor bad. Bubonic plague is natural. Cancer is natural. Death is natural. In spite of these things being natural, I do my best to avoid them as long as possible.
Next time, more of what’s in the water.
Gardner lives in Keller and is the UGA extension agent for Glynn County, serving South Bryan.