Thomas J. Koske | 6/24/2005 12:53:27 AM
Lawn grasses are now showing spring re-growth across much of the state, but LSU AgCenter horticulturist Dr. Tom Koske warns against rushing out and applying fertilizers that will cause too much very early growth.
"Putting fertilizer on too early in the spring will feed pesky winter weeds," the horticulturist warns, adding, "If put on heavily, plant food will create a lush, weak growth of grass that will be sensitive to brown patch, leaf spot and other diseases."
Koske says to let the grass awaken gradually and show definite activity. Mow new growth once or twice before fertilizing, he says. Start with a complete fertilizer like 12-4-6 or 13-13-13 if you know that your phosphorus is not too high, he suggests. If you have zoysia, St. Augustine or bermudas, use 7 to 8 pounds per 1,000 square feet. A product with a slow release action is preferred. On centipede or carpet grasses, use 4 to 5 pounds per 1,000 square feet.
After that application, use a nitrogen fertilizer or a turf blend at a rate of one-half to 1 pound pure nitrogen per 1,000 square feet each. On centipede and carpetgrass lawns, he recommends only one to two more applications this year using one-half pound of nitrogen per 1,000 with a complete fertilizer blend.
Koske says to beware of a fertilizer that also has a weed killer in its formulation, because some herbicides are meant only for use on bermuda and zoysia lawns, so read the label first. Herbicides with 2-4D are best applied as liquid sprays. Keep such fertilizers/weed killers out of the flower bed, if so advised. Weed-and-feed products are often a good choice for spring lawn maintenance, if weeds are present.
Turf fertilizers with a high percentage of nitrogen and lower phosphorus and potassium are usually the best choice for a feed during the growing season.
If you wish to de-thatch or power rake this year, wait until late spring when the turf is actively growing. Large dead areas are probably die-outs from winter kill or brown patch diseases. If your soil test indicates a need for lime, apply lime in early spring or wait until mid-fall and cooler.
Broadleaf weeds often can be controlled using selective post-emergence formulations that contain two or more herbicides. Formulations of a 2-4D are spray blends available for most southern grasses.
Most labels will stress use on younger weeds growing in the cooler mid- to late-spring. A temporary discoloration of the lawn usually occurs, and a second application two or three weeks later is usually needed.
Related yard and garden topics are available by contacting an extension agent in your parish LSU AgCenter office. Also, look for Gardening and Get It Growing links in the Feature section of the LSU AgCenter Web site: www.lsuagcenter.com.