Good rule of thumb is you get out what you put in. That's without any problems.
A few years ago I put 100 or so seeds into one little patch of worked soil just for the hell of it. Every year since 5-10 seedlings pop up from that spot, sometimes i'll transplant the healthy ones into another location. Amazing that they sit there year after year thru the winter freeze and a few still come up years later. None have ever survived the summer without care.