Answer: The spray on grass is hydroseeding, but in order for it to work you would still need to prepare the soil just as you would to plant grass seed or sod the normal way. You will still need to till the area to loosen the soil, then level the soil, remove the surface stones and rake it smooth to get a good result either way. This might be a case where adding topsoil would help, or you might need to add a generous amount of good quality compost prior to planting. I suggest you consult with your local county extension for advice based on knowing the soil in your yard currently and running some basic soil tests. In the meantime, here is more information about hydroseeding.
Good luck with your side yard!
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