News Release Distributed 12/10/10

By LSU AgCenter Horticulturists Dan Gill, Kyle Huffstickler, Allen Owings and Ron Strahan

The late fall through late winter months are the bleak time of the year for most lawns in Louisiana. Warm-season lawns across much of the state will go into some state of dormancy by early December, and re-growth will not commence until late March or early April.

Because lawns are not actively growing, fertilizer applications are not needed during the winter. In fact, nitrogen fertilization should have ceased on home lawns by late summer (mid- to late August for St. Augustine grass and centipede grass). Many home gardeners incorrectly apply nitrogen fertilizer in the fall months, and this is not a good idea.

Nitrogen fertilizer on dormant to semi-dormant St. Augustine grass, centipede grass, Bermuda grass and zoysia lawns can lead to increased brown patch and winter kill. Also, nitrogen applications during this time have a greater potential for leaching of nutrients into non-target areas.

Winter is an excellent time to collect soil samples and submit them for analysis. Samples should be a composite of soil taken from about 3 to 4 inches deep at various places around the lawn. To get your sample tested, bring about one pint of soil to your parish’s LSU AgCenter office or to a participating garden center. Make sure to specify the type of grass you are growing on the soil test form. Soil samples submitted to the LSU AgCenter cost only $10, but they provide a wealth of information concerning the overall fertility of your soil.

If results of the soil test indicate the soil pH is too acidic, lime will be prescribed in the soil test recommendations. Winter is the best time to apply lime so it can be fully activated by the following spring. The correct soil pH is extremely important and has everything to do with nutrient availability to your lawn’s roots and to fertilizer performance.

Postpone establishing any permanent warm-season turfgrass from seed until next spring. Sod, such as St. Augustine and centipede grasses, can be laid during winter, if necessary, but remember to keep it moist to prevent it from drying out and dying. Establishment is easiest when it’s delayed until the middle of spring, well after spring green-up.

Brown patch disease can come and go throughout the winter if the weather is mild. It can be treated with fungicides for control. The fungicide azoxystrobin is now available as a granular product and is one of the best fungicides for managing brown patch disease.

Damage from brown patch will slow spring green-up, and affected areas will remain unsightly until warmer spring weather conditions allow for turfgrass recovery. Lawns may begin to show signs of green-up in south Louisiana in late February.

Do not push turfgrass growth with fertilizer at that time. Fertilizer applied too early will feed winter weeds and result in lush turf growth that is more susceptible to injury from late frosts or brown patch. Lawns may be fertilized in the New Orleans area by late March, but delay fertilizing lawns in the Baton Rouge area until early April and begin considering fertilizing lawns in north Louisiana in mid-April.

February and March are good months to spray broadleaf-type winter weeds while they’re still actively growing. Also, herbicides containing three-way mixtures of 2,4-D plus dicamba plus mecoprop can be used for winter broadleaf control in all southern turfgrasses at this time of year.

Because weed-and-feed products usually contain high levels of nitrogen fertilizer, however, any application should be delayed until the appropriate time for applying nitrogen-containing fertilizers. A weed-and-feed treatment can be substituted as your first application of fertilizer during early spring.

Visit LaHouse in Baton Rouge to see sustainable landscape practices in action. The home and landscape resource center is near the intersection of Burbank Drive and Nicholson Drive (Louisiana Highway 30) in Baton Rouge, across the street from the LSU baseball stadium. For more information, go to www.lsuagcenter.com/lahouse and www.lsuagcenter.com/lyn.