I agree with greeneyes - sounds like too much nitrogen. That will get you leafey greens, and not much else.
Have you ever done a soil analysis, like thru Co-Operative extension ?? (N/P/K or soil Ph {acidity/ alkaline}}
Also , do you germanate seeds indoors , or do direct seed planting , or start with established plants ?, or plants from the store ?
Before you remove all the soil, do a study on the soil first, and minimize your investment expense.
Is there a way to balance out the nitrogen? Or is this something that can’t be fixed?