Answer: If you are trying to start or renovate a lawn or garden area, you would first need to run some basic soil tests and determine from the test results how much fertilizer is needed and if you need to add lime to adjust the pH.
Before tilling you may need to kill off the existing vegetation by using an herbicide containing glyphosate. Read and follow all of the label directions, including any waiting period. For a garden area, you might prefer to use a rented sodcutter to remove the existing lawn grass. The sod can be replanted elsewhere or composted.
When starting a lawn or garden area it is usually a good idea to add organic matter such as compost during the soil preparation phase and work that into the top six inches of soil. The tiller will break up the soil and work the compost through it.
After tilling you will need to level the area and remove debris such as weeds and larger stones. Also break up large clods and rake the surface smooth. At that point you are ready to plant seed or sod, or set out your garden.
I would suggest you work with your state extension service on the soil testing; they can help you interpret the results and also suggest the best varieties of grass/plants for your local area. They can also help you develop a regular maintenance plan. Here is their web site including contact information.
Finally, please keep in mind that late summer to early fall is actually the best of time to start a lawn or do extensive lawn renovation.
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