Answer: Your first step should be to run some basic soil tests and find out where the pH is right now. Based on the tests results you will know whether or not you need to lime. (Lime lowers the pH and is used to bring acidic soil to an acceptable range for lawn grasses.) Lime is long lasting in the soil and only needs to be applied every few years. It would not affect the texture of the clay. Whether or not to use a weed killer would depend on what kind of weeds are in your lawn and on the overall health of your lawn. Healthy turf is able to crowd out many weeds, especially if it is mowed correctly. I would suggest you work with your county extension to run the basic soil tests and develop a turf care program for your specific soil and grass type. Here is a link to Maryland specific lawn care information from your county extension.
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