Answer: You may be able to overseed the existing lawn without tilling, yes. However there are many factors that affect the success of a lawn. I would suggest you start by running some basic soil tests to check fertility and also check the pH to see if you need to apply lime. You might also want to do some core aeration and then top dress with compost to try to improve the soil. Regular mowing is probably the best thing you can do for your lawn. Cut it at a height of 2 to 3 inches and mow often so that you never cut off more than one third of its height at a time. Early fall is the best time of year for seeding. You may want to try these other approaches first and then possibly seed again in the fall. In the meantime, your local county extension should be able to help you with the soil testing and interpreting the results. They also have information about lawn care at their web site you may find interesting.
Good luck with your lawn this summer!
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