Answer: Most fertilizers should be thoroughly watered down into the soil (or rained on) before you allow pets or people to contact the area. Products that also contain a weed killer or herbicide (such as weed and feed products) or those that contain pesticides often have different waiting periods and special application instructions. It is really important to read the label on any product you consider using and carefully follow the instructions.
One of the safest methods to add nitrogen to your soil is to allow your grass clippings to stay on the lawn and recycle -- it essentially fertilizes itself.
The best fertilizer and also best seed to use would depend on the soil conditions in your yard. I would suggest you work with your local Cornell county extension to run some basic soil tests and determine how much to fertilize and if you might need to lime for best results. They should be able to help you with which type(s) of grass to plant as well.
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