Answer: There are many possible reasons for brown patches in lawn including pest, disease, and dog urine for a few examples. I would suggest you consult with your local Cornell cooperative extension for help in diagnosing the cause of the spots and work from there.
As a new home owner, you might want to begin your routine lawn care program by running some basic soil tests to check fertility and soil pH levels. Then you would add fertilizer and/or lime as indicated by the test results. (The only way to know the correct amount to use is to test the soil.)
Late summer to early fall is the best time to do serious lawn work such as seeding, so that gives you time to get the test results first. (July and August are the worst months due to the weather being typically hot and dry.) Your county extension should be able to help you with the testing and interpreting the results.
Also, their web site offers some month by month care and trouble shooting information you may find helpful. (You may need to cut and paste the complete url into your browser to make it work correctly.)
Good luck with your new lawn!
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