Fall not time to fertilize lawn

September 18, 2013 

It is that time of year again when we start to see advertisements for feeding fall lawns. Feeding, also known as fertilizing, turfgrass in the fall is unnecessary and can cause more harm than good.

The biggest problem with these commercials is that they are too vague. They are run nationally and do not specify which grass species the fertilizers should be used on. These commercials show a homeowner standing on a lush green lawn. Your first reaction should be that this cannot be a warm season turfgrass.

Most lawns in South and Middle Georgia consist of three grasses: Bermuda, centipede and St. Augustine. Warm-season grasses grow in the late spring and summer and go dormant in the fall. Once we have our first frost, usually about late October/early November, these grasses turn brown and go dormant. The purpose of our grasses going dormant is to survive the cold weather.

To prepare for the colder weather, grasses take energy away from the leaves and direct it to the roots, rhizomes and stolons. This storage of energy is what allows the grass to survive during the winter months and green back up in the spring. Late application of fertilizer, especially nitrogen, will cause the grass to produce new/top growth. This new/top growth is easily killed by cold weather and also diverts the grasses’ energy from the storage structures.

September is the last month that I would recommend fertilizing turfgrass, except centipede or if I had not been able to fertilize earlier in the year due to weather conditions. People tend to overfertilize centipede. Centipede only needs one pound of nitrogen per 1,000 square feet per year. Most of the warm-season grasses require 3 to 7 pounds of nitrogen per 1,000 square feet per year. This fertilizer is usually applied in three to five applications during the growing season.

All turfgrasses in Georgia have a recommended rate of fertilizer that should be applied and not exceeded. In Georgia, we do not have any of the cool season grasses that would need fall fertilizer.

Now is a great time to take a soil sample of your lawn. This will give you plenty of time to apply lime if it is needed for the next growing season. An important factor in plant growth is soil acidity level. This is measured in terms of a pH scale which is graduated from 0 to 14 with 7 being neutral. Any number below 7.0 is considered acidic. Any number above 7.0 is considered basic.

Most turfgrasses, with the exception of centipede and carpetgrass, grow best at a pH of 6.0-6.5. Centipede and carpetgrass grow best at a pH of 4.5- 5.5. A pH either too low or too high will reduce the availability of plant nutrients, meaning the nutrients cannot be absorbed by the plant.

I always recommend a soil sample before fertilizing, so you are not wasting money on unneeded nutrients and potentially harming your turf.

Dates to remember

• Sept. 19: Show CAES UGA Southwest-UGA Tifton Campus Conference Center. Contact The Office of Academic Programs 229-386-3528.

• Sept. 24: Show CAES UGA Southwest-UGA Tifton Campus Conference Center. Contact The Office of Academic Programs 229-386-3528.

• Oct. 9: Walk Georgia registration deadline.

• October 3-13: Georgia National Fair, Perry-Ask a Master Gardener Booth in Heritage Hall, Demonstrations daily.

• October 15-17: Sunbelt Ag Expo, Moultrie-www.sunbeltexpo.com.

Charlotte Mote is the Houston County agricultural and natural resources agent. Contact her at 478-987-2028 or cmote1@uga.edu.

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