Ag Line: Winterizing Your Lawn
By Wade Parker County Extension Coordinator

At last, it seems as though fall is in the air! The temperatures have cooled down and a very slight chill was in the air Sunday evening. However, it does appear some 90-degree days are still in the forecast the next few days.

If you have not noticed your lawn lately, the grass is not growing as fast as it was three weeks ago. As the nighttime temps decrease, warm season grasses will not grow as much. As this slowdown occurs, homeowners may want to "winterize" their lawns. The term winterize refers to beefing up plant levels of the nutrient potassium (K). This is an attempt to toughen plant tissues for the winter freezes much as you would add antifreeze to your car's radiator for freeze protection.

Research has shown that higher levels of plant K enhance tolerance to a broad range of environmental stresses, including cold damage. A good strategy is to maintain high levels of soil K throughout the growing season. This can be accomplished by applying 15-0-15 or 16-4-8 during the season. Keep in mind that the end number of a fertilizer analysis refers to the percentage of potassium in the bag.

With high K available all season, special winterizing would be unnecessary and the turf would be in the best shape to handle environmental and pest problems all season long. Just make sure your last application of N is lower (maybe half rate or less) when applied after late summer and before mid-fall. After mid-fall, do not apply N to a warm-season lawn.

For those with a less-thanideal lawn fertility program, here are some end-of-season tips:

(1) Reduce N fertilizing to 1/ 3 normal application or less. If you have not fertilized your lawn by September, you should not try to continue to grow it out in the fall and risk extra winter kill. Reducing N fertility slows growth, which allows the grass to toughen and store more carbohydrates in reserve for spring green-up. Lower fall N also reduces Brown Patch (Large Patch) disease, which is so prevalent in fall.

(2) Keep up adequate moisture in the fall. We often want to forget lawn care by this time.

(3) Finish the growing season with a fertilizer high in potassium. If applying only K2O to extra fall N, use 1 to 2 lbs./1,000 sq. ft. of muriate of potash (0-0-60). This supplies a 60% K2O or up to 1.2 lb. K2O/ 1,000 sq. ft.

(4) Always apply granular materials on dry foliage. This reduces the salt burn potential of an application. They are usually watered in if rain is not forthcoming.

One last warning is offered. Too much of a good thing is often bad. Excessively high rate of K fertilizer may lead to foliage burn (salt burn) or can lead to competitive inhibition of other soil nutrient uptake. This is especially known to affect magnesium (Mg) uptake, which can appear as a light green lawn color.

If you have not been fertilizing your lawn all year, then I highly suggest adding an application of potassium. I feel that an application of potassium will help a lawn survive a harsh winter!

The University of Georgia Cooperative Extension offers educational programs, assistance and materials to all people without regard to race, color, national origin, age, sex or disability.