Top dressing and reseeding a lawn #726403 - Ask Extension

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Top dressing and reseeding a lawn #726403

Asked September 23, 2020, 3:56 PM EDT

Dear Cooperative Extension: What should use to top dress my lawn this fall? I was thinking of using Leafgro for the top dressing, or is it better to use topsoil, or a mixture of the two? I have regular fescue (cooler weather) grass and trying to get rid of the clover, by digging it out and/or using IronX. This is leaving patches with no grass or thin grass that I want to reseed, along with top-dressing the whole lawn to give it more organic matter. I live in Silver Spring, MD and did a whole battery of soil testing through your office in 2017. The soil pH was in the optimal range (around 6.8 on average across the front and back lawns); while the P, K, Mg, and Ca were all in the excessive range. The organic measured 10.6% in the front lawn and 8.2% in the back lawn. Thank you!

Montgomery County Maryland

Expert Response

Hello,
Being that your lawn has excessive amounts of organic matter you should not be adding ANY organic materials going forward.  The ideal range of organic matter content is 2-5% and you are way above the recommended amount.  You actually need to REDUCE organic matter.  There are a couple ways to do this.  One is lawn aerification.  The second is verticutting (aka: vertical mowing).  Either of these pieces of equipment can be rented at almost any rental equipment place.  Lowes, Sunbelt, united etc... Or, you can contract the job to a lawn company.  Most companies provide this service.  Aerification or verticutting should be part of your yearly maintenance programs.  Once in fall, and once in spring. See attachment for aerification plug.  This machine will pull cores/plugs from your lawn helping reduce organic matter, increase water infiltration, help root proliferation, and increase gas exchange.  A verticutter will cut and remove organic matter and thatch from the soil layer and provide the same benefits as a aerification.
Also, the spraying of the your weeds with ironX might not be the best solution.  There are many herbicides that will completely control most of your broadleaf weeds.  IronX is simply just iron (a plant nutrient), and the weeds could possibly come back and result in low control %'s and a waste of your time/money.  If you have more questions please reach out.
John Emerson Jr. Replied September 25, 2020, 10:34 AM EDT
John: We appreciate your guidance. What products do you recommend for controlling clover which is our primary nemesis? Please nite that we also lay down WOW (corn meal product from Gardens Alive) in the late winter when the forsythia bloom as a weed prevention and lawn nutrition agent. 
The Question Asker Replied September 26, 2020, 1:50 PM EDT
John: We appreciate your guidance. What products do you recommend for controlling clover which is our primary nemesis? Please nite that we also lay down WOW (corn meal product from Gardens Alive) in the late winter when the forsythia bloom as a weed prevention and lawn nutrition agent. 
The Question Asker Replied September 26, 2020, 1:50 PM EDT
Hello,
There are many many products to control broadleaf weeds.  Trimec by PBI/Gordon would be sufficient.  Fertilizing in the winter is never a good idea.  The window for fertilizing cool season grasses is in the late summer to late fall (now).  Again,  WOW is an organic product and should be avoided. I don't know the exact active ingredients in the product, but I would bet that it does a very poor job at preventing weed germination.  There are close to zero organic products that are good herbicide, fungicide, or insecticide options.
John Emerson Jr. Replied September 26, 2020, 9:35 PM EDT

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