I’ve received a dozen or more phone calls during the past month or so regarding lawn care. The majority of the callers have either inquired into the proper timing for fertilizing their lawns or applying herbicides to control weeds. We are now in the middle of March, but in most cases it is still too early to start pushing early growth of turf grasses with lots of fertilizer. For one, turf grasses, such as St. Augustine, centipede, and Bermuda, undergo spring root decline. During this time, the majority of the old root system dies and the grass grows new roots.

If the fertilizer is applied during the time of spring root decline, the grass puts effort into growing the leaf blades when it really should be putting that effort into producing new roots. Our warm-season permanent grasses will really start growing once the weather warms up and soil temperatures are somewhere in the high 60s at a 2-inch depth. Once the lawn greens up enough to warrant a second cutting, a fertilizer program should be implemented to insure the lawn is receiving adequate nutrition.

When the time comes to determine what type and how much fertilizer to use, it is best to fertilize according to the results of a recent soil test. Without the soil test results, you can really only assume an average application of soil nutrients. That being said, stay away from the lime and opt for an average turf-blend fertilizer. A fertilizer with an analysis that has about a 3:1:2 ratio of N:P:K would work. St. Augustine grass is typically fertilized three times a year: the middle of April, June, and August. For centipede grass, one application in April is usually sufficient.

When it comes to mowing the lawn, you never want to remove more than the top 1/3 of the foliage in any one cut. St. Augustine grass should be mowed at a height of 2 ½ inches for grasses in the sun to 3 ½ inches for grasses in the shade, while centipede and common Bermuda grasses should be mowed at a height of 1 to 2 inches tall.

Water only as needed. There may be weeks when no water is needed at all. Overwatering can lead to several lawn diseases which you want to try to avoid if at all possible. Lawn irrigation is typically minimal during the spring until May. Watering in the early morning hours is recommended because it is the most efficient. Midday watering is not as efficient because some of the water evaporates before getting into the soil. Additionally, watering during the evening should be avoided. If the water stays on the grass blades for extended periods of time, this may favor the growth and development of turf grass diseases.

There are pre-emergent herbicides available on the market that can be used on the lawn to prevent weeds from appearing. If weeds are already present in the lawn, this is the time to incorporate a post-emergent spray program. It is best to use the post-emergent spray early in the spring (April and May) because as temperatures continue to rise, so does the chance that turf injury will occur as a result of using the post-emergent herbicides. Another thing to keep in mind when selecting a herbicide is to make sure the herbicide is safe for use on the type of lawn you have.

For more information about this or other topics contact Sara Rogers, Jackson Parish County Agent, with the LSU AgCenter at 318/259-5690 or by email.