Sid Mullis: Last call for lawn fertilizing

Planting turfgrass
A Richmond County Trees and Landscaping grounds keeper spread fertilizer on Augusta Common in 2008. Warm-season grasses should not be fertilized after Sept. 15. "Fall feeding" advice is for cool-season grass.

This is the last call for fertilizing your lawn – if it needs it, that is. Around Sept. 15 is the latest we like to fertilize our warm-season grasses.


You can ignore the commercials that tell you to “fall feed” your lawn. Those late September/October commercials are aimed at cool-season grasses such as fescue, which we don’t grow here.

Sept. 15 is the magic date for a couple of reasons. One, the grass is slowing down at this time and it will not use the fertilizer very well. A high-nitrogen fertilizer at this time also will make it less cold-hardy going into the winter. The grass needs to be slowing down and not speeding up.

The other reason is that turf diseases, such as take-all patch and large patch, are much more active during the fall. They thrive when temperatures are in the 80s during the day and in the 50s and 60s at night. Since the grass is slowing down, it can’t fight them off as well. If your grass has one of the diseases or is susceptible to one or both of the diseases, fertilizer can make it worse.

Let’s go back to whether your grass needs fertilizing or not. Our different warm season grasses have different needs when it comes to fertilizer. Take hybrid bermudagrass for example. In a high maintenance program, you can fertilize as often as every month starting April 15. On a low- maintenance program, you should be fertilizing about every two months. This would normally be three fertilizations for the growing season. So if you follow a low-maintenance schedule and you just fertilized four or five weeks ago, it doesn’t really need it again.

The normal fertilizer frequency for the other grasses is as follows:

Common Bermuda, St. Augustine and zoysia – high maintenance: It would be the same as for the low maintenance on the hybrid Bermuda; every two months. For low maintenance, make your first application on April 15 or shortly thereafter and once more during midsummer.

For the centipede high maintenance program, make the first fertilizer application around May 1 and do it once more during the middle of the summer. For low maintenance, fertilize once every other year. As you can see, centipede doesn’t need much. Some of the prettiest centipede lawns I have seen are those that almost never get fertilizer.

Which type of fertilizer should you use? Only a soil sample tells you for sure.

In the absence of that my favorite (and the most balanced) is 16-4-8. Unfortunately, 16-4-8 has become harder to find in the Augusta area. A garden center that is smart will always keep it stocked.

Whichever fertilizer you find and buy, get one that contains 8 percent or greater of potassium. I would say that about 95 percent of all lawns in the Augusta area are deficient in this nutrient, yet it is extremely important when growing grass.

Adequate amounts in the soil helps ward off diseases and makes your grass more winter hardy.

At a normal application rate, you want to apply enough fertilizer to put out 1 pound of nitrogen per 1,000 square feet. To get this, always divide the percent nitrogen into 100. For example in the 16-4-8 fertilizer, dividing 100 by 16 gives you 6.25 pounds of fertilizer.

For those who want to fertilize organically, there are certainly products you can choose. There are manure fertilizers such as Kricket Krap, CricketPoo or milorganite that can easily be broadcast over the lawn. You can also choose a composted chick-based manure. You can apply rock phosphate for your phosphorus source and green sand for potassium. Going natural does not mean you have to let your lawn go to pot.

Planting  turfgrass

Is it too late to plant grass? Yes, and no. It is too late to plant most warm season grass seed, whether it is common Bermuda, centipede, or zenith zoysia. You might get away with planting Bermuda because it takes about two weeks to germinate, but once it comes up, the weather will be cooling off so much that it will not grow much after germination. For the most part, if you need to plant grass seed to hold the soil, consider annual ryegrass as a temporary cover until next spring.

When it comes to sodding or sprigging, it depends on which one of the four grasses you plant. Oct. 1 is about the latest you should plant centipede or St. Augustine. The grass needs about four to six weeks to develop a good root system before it goes completely dormant after a couple of frosts. If these grasses don’t develop that root system, there is a large risk it could be killed during the winter.

This is really not as much of an issue with Bermuda and zoysia as they are much more hardy. But the downside of planting Bermuda and zoysia well after Oct. 1 is, when they don’t root down much, you may have to keep them watered much of the winter until growth resumes in the spring.