Utah Pests News Fall 2008

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Fall Lawn Tasks

By Dr. Kelly Kopp, Extension Water Conservation and Turfgrass Specialist in the Department of Plants, Soils, and Climate at USU.  For more information about Kelly and turfgrass research, click here. 

  This drought-stressed lawn would benefit from proper mowing, watering, aeration, and fall fertilization.
  Core aeration helps to alleviate compaction.
There are a number of things that you can do to prepare your lawn for the winter and to ensure that it comes back strong in the fall with an inherent ability to withstand insect and disease pressure. The cool night temperatures that we are currently experiencing are probably already strengthening your lawn after the hot and dry summer. You may be noticing improved grass color and density. Now is the perfect time to enhance your grass’s recovery with a few simple steps.

After the summer, it is very likely that your lawn needs some supplemental fertilization. Nitrogen will be needed in the largest quantity and you should apply 1 pound of slow-release nitrogen fertilizer per thousand square feet of lawn. This will help the lawn to recover from summer stresses and will further improve grass color and density.

Fall is also an ideal time to aerate your lawn if the soil is compacted or there is a significant layer of thatch beneath the grass. The types of grass typically grown in Utah do not usually produce thick layers of thatch under normal conditions, but it is possible, especially where too much water and fertilizer have been applied. If the thatch underneath your lawn is more than ½ inch thick, consider core aeration to stimulate the natural decomposition process. Likewise, if you have a very fine-textured soil, compaction may occur, particularly in high traffic areas.

As the cooler weather intensifies, you will also be able to cut back on lawn irrigation. It’s easy to forget that changes in the program of your irrigation controller are necessary at this time of the year. The grass does not need as much water as it did during the heat of the summer and it’s the perfect opportunity for you to contribute to water conservation efforts. A great deal of water is wasted in the fall because irrigation controllers are not adjusted for the cooler temperatures.

As the weather gets even cooler and winter is just around the corner, you will notice that your lawn is growing much more slowly. At some point, you will perform your last mowing of the growing season. This is a critical time in the life and health of your lawn. Hopefully you have been mowing at a height of 2 1/2 –3 1/2 inches to promote root growth and stress tolerance and have been recycling the clippings back into your lawn. These are good practices, but not for your final mowing of the season. The last mowing should be much shorter, from 1 to 1 1/2 inches, and you should remove the clippings. Mowing at this shorter height will not leave long grass blades standing that over the winter, can lay over and increase humidity beneath snow cover. If the grass blades are very long, and there is lengthy snow cover, the disease called snow mold can occur.

After your last mowing is also the best time to apply your last fertilization of the growing season. Once again, nitrogen is of primary concern. Following this mowing, you’ll want to apply 1 pound of quick-release nitrogen fertilizer per 1000 square feet of lawn. It’s important that the nitrogen source be quick-release so that the grass can take it up before going dormant due to cold. This is probably the most critical fertilization of the entire growing season and should not be missed! Research has shown that this late fall fertilization provides the most benefit and drought tolerance to the lawn the FOLLOWING summer.

These simple steps will ensure that your lawn rests well over the winter and starts out in the spring healthy and strong.