weed control in lawns #342356 - Ask Extension

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weed control in lawns #342356

Asked July 12, 2016, 10:57 PM EDT

My church has a large lawn. A crew of volunteers mows each week. There is a great deal of weed growth throughout the lawn. Are there any cultural practices/fertilizers/herbicides you could recommend for weed control? We would prefer to use environmentally friendly practices first. The lawn is in full sun most of the day. My understanding is that mower height should be 3" to shade out weeds. Any other recommendations you have would be appreciated.

Washington County Minnesota

Expert Response

Thank you for the question.  A properly maintained lawn has grass growing so thickly that weeds don't have much chance to establish and grow. You are correct in understanding the 3 inch height rule related to mowing.  Grass at this height will shade the soil, making it hard for some weeds to germinate.  At this height it has a chance to grow deeper roots which help each blade get access to more moisture and nutrients making the entire lawn tougher and able to withstand some drought and disease, requires less supplemental watering and fewer chemicals.
If less than 50% of the lawn is weeds and/or bare spots, you may be able to make modifications in basic lawn care practices or improve site conditions to bring the lawn back to good health so that renovation or starting over isn't needed.  
First of all, we suggest you get a soil test to find out just what your soil needs before doing anything.  There is a small fee but results will guide your crew in knowing what is needed.  Here is how you do it:  http://soiltest.cfans.umn.edu/
While you wait for the results (a few weeks) immediately institute the new mowing height of 3 inches.  Perhaps some volunteers could walk around and manually remove the largest weeds to reduce the weed load.  If herbicides aren't objectionable, you could make use of them to get the weeds under control.  After you get the results, you will know what amendments are recommended for your soil.  Your crew may need to aerate, add certain fertilizer kinds in specific amounts, and add organic matter like compost and then overseed.  Note that overseeding is recommended to be done mid August-mid September because weed growth and competition has slowed down and cool, moist weather starts to move in which is ideal for seed establishment before winter sets it.
Read the following links to learn how to proceed if you find that the church lawn needs more than basic care improvements:
Anita Hoaglund Replied July 14, 2016, 4:27 PM EDT

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